Around $500/night to stay at the Grand Californian at Disneyland. It was nice to do once, but I don’t think it’s worth an extra $350/night to stay there over one of the other hotels near Disneyland. You don’t even get free breakfast, and the rooms were nothing special (except for the omnipresent mickey motif). The main lobby is amazing, but you don’t have to be a hotel guest to enjoy it.
We stayed here about eight years ago. IIRC, we spent about $300 a night.
I had a meeting there, and it was $300 a night, but I think my conference arranged a decent rate. It seems to have gone downhill - the first time I stayed there about 5 or 6 years ago it was much nicer. Then Disney was trying to get our business so it was free.
On my own dime I think the max was $150 a night in the Holiday Inn in Manhattan, 58th street or so. I’ve stayed in nicer places there but it was a long time ago and thus cheaper.
Best room ever was the Presidential Suite at the Hyatt in Santa Clara - but that was our conference hotel so it was free. 
I don’t think I’ve paid more than 180 USD a night for a room, personally.
If you count the “All inclusive package” for our honeymoon, which was ~3k or so for 6 nights / 7 days, but that included all food and drink, the rooms themselves were paid through the AFVC which were something like 345 dollars for the whole week, it might be the most expensive place I’ve stayed (it was a wedding gift, so not out of my pocket)
We stay at the Westin, which runs in the 200-300 dollar range but we only ever stay there when we have enough points saved up. Our last, non Westin stay was in a Hilton running about 170 dollars after taxes.
To update my answer from when this thread was first alive–I paid ~$260 a night to stay at Portmerion. But I didn’t just get a nice room for that price–I got to live in the Village for 2 days, and whenever I see the bay windows of the Bridge House over Patrick McGoohan’s shoulder in an episode of The Prisoner, I can say “My house!”
Probably around $300 at a Courtyard Marriot in the middle of South Beach’s Art Deco district. Was just for the location too since it didn’t have a restaurant except for an alleged breakfast buffer I didn’t see (and a pool but I’m not a pool guy). Was only a couple blocks from a Coheed and Cambria concert I was seeing.
$335 per night for a big suite at the Doubletree in Times Square. This suite normally goes for $200 more than that but there was a sale.
The most expensive room I’ve stayed in was a two-bedroom suite at an Embassy Suites in Waikiki but I didn’t pay for it. I had booked a one-bedroom with points but when we arrived they said that we’d been upgraded to a two-bedroom suite. It would have been $700 a night if we’d paid for it.
Nm
$180/night for three nights at The Inn at Longwood Medical in Boston. I was there for Anime Boston and it was well worth it.
A few years back, my wife and I spent an anniversary at the Trump tower hotel in Chicago. It was ~$500 although we covered it with credit card travel points that were about to expire anyway, otherwise we wouldn’t have gone.
It was a very nice room although we chuckled at stuff like the fancy bottle of Trump Water for some ridiculous price (probably north of $20)… We had brought a bottle of wine we bought on our Italian honeymoon but no corkscrew. They sent a guy up but he was having trouble so he took it to their wine-guy (that’s the ritzy term) who opened it but could tell that it had turned so they sent it back up with a bottle of champagne “Compliments of Mr. Trump”. I wouldn’t spend that much out of pocket for the experience but it was nice to do it the once. Not voting for the guy but, when his name comes up in conversation it’s fun to say “Yeah, but he does have a nice hotel…”
About $140 a night out of pocket, just north of $200 if reimbursable as a professional expense.*
since the expense account is not unlimited, I resist paying through the nose when going to meetings held in the Grand Sriracha Latour Hotel. I am well known in the family as a cheap bastid who will make reservations at a much cheaper place near the venue (I make up some of the difference to Mrs. J. in the form of a couple nice meals out).
I still have fond memories of my $10/night suite at the Motel “H” in Murdo, South Dakota. Pillows were kinda lumpy, but an unforgettable atmosphere.
***home of a renowned doll museum, which I had to skip 
since we were just passing through.
$200 Canadian in the Niagara Falls region in the first week of July - a holiday week in both countries. It was at a no-frills Best Western; I went there when I walked into the higher-quality Holiday Inn across the street and they told me a room would be $300.
I always take the soap anyway when I travel; I also took the bottled water, granola bars, and even the toilet paper. 
My credit card bill said it was about $140 with the exchange rate. This was in 2002.
Over $500 per night. It was marvelous
I think it must be the US$250 a night we paid for our room at the Carlton Hotel in Singapore two years ago. That represented a substantial discount from the regular rate, because we booked and paid a couple months ahead of time and agreed to no cancellation. I think I saw the walk-in rate listed on the counter as US$400-something, close to US$500. That’s US dollars, not Singapore dollars. Nice room. We could have found cheaper but lower quality and/or poorer location. This place was just about right. We’d stay there again.
At the other end of the spectrum, the cheapest may be the US$2 a night for a cot in a cubicle in a Khao San Road guest hose in Bangkok in the 1980s.
I stayed at The Bellagio in Las Vegas about a decade ago. We stayed in the penthouse suite and it ran $750/night. But it was awesome, there was a Jacuzzi, two bathrooms and a steam room. We drank Dom P all night. Good times.
To add, that was the most I’ve personally paid. But now that I think about it, my room at the Conrad in Hong Kong in 1996 cost about the same, although someone else paid for that, and I had to share. (And I learned that was the cheapest room, plus I think a discount was involved.) The same with my stay at the airport hotel in Osaka, Japan that same year.
Twice my microsoft millionaire son treated my wife and me to a week in Hawai’i that cost about 700-800 a night. On my own dime we rent a villa in Barbados for three weeks every year for about 170 USD a night. Dirt cheap if we can get one or even two other couples to share it.
I think I have paid as much as $200 a night at conferences, but that is not paid by me. Even so, I resent it. When I went to a conference in Ottawa last October it cost my grant $115 a night, plus around $15 for parking.
Now that I’m a little older and wiser, I’ve spent maybe $200 or so on hotel rooms at weddings. Nothing special, but you get roped in to staying with the crowd. For work travel I’ve stayed in places up to around $300, generally in places where there isn’t a lot of middle ground between the over-luxurious and the patently unsafe.
I still find hotel spending to be the least marginal bang for my buck when traveling. A $100 hotel doesn’t make me twice as happy as a $50 hotel. A $200 hotel probably doesn’t make me even a slight bit happier than a $100 hotel. I appreciate that nice and luxurious places exist, and I’m happy to hang out at their bars or pop in for brunch. I just don’t get a lot of joy out of actually sleeping there. At their core, nearly all hotel rooms feel institutional and a bit dingy to me.
Probably around $500 a night. The last time was for a corner suite in a hotel in Chicago with a beautiful view of the lake. We were there for the Blues Festival and were staying just a couple of blocks from the venues.
We spent somewhere in the low $300s per night for two nights in Venice.
It was worth it.