We’ll be married 15 years in the Spring. We want to do something unique & memorable. Dinner and a movie just won’t do. No parties, skydiving, or bungee jumping. Just the two of us. Nothing we have to travel far to accomplish (Texas). Budget is only a minor consideration, but within reason.
Ideas?
You ruled out a lot of choices already. How about a night at a luxury hotel?
Run the Tough Mudder in May.
There is an inn in Lake Tahoe called the Fantasy Inn. It’s a place for adult couples to be, well, couples. It’s not sleazy, but is definitely sexy. Check out the website.
I assume there are similar places in Texas somewhere that are similar.
J.
The symbol is crystal - how about a glassblowing class where you can create mementos of the day?
15 years is nothing. 25 years - now you’re talking. At 15 years you would have a small get-together at which you would primarily discuss how great it’s going to be 10 years from now, when you get to 25 years. As for what to do then - well you have 10 years to work on that one.
Nothing? It’s not about comparing, it’s about celebrating our lives together, and every year matters to us, even the little ones. But congrats to you for your 25! That’s wonderful too.
I like the idea of making something together. We’re both pretty creative. After doing some surfing on crystal, I found out we can get a chandelier kit and make our own! That would give us both a project and a keepsake. And crystal! 
Sorry, I was just kidding. 15 years is quite a big deal, especially these days when people marry late and divorce early.
Happy 15th and I hope whatever you end up doing captures the moment.
We’ve been there. Some of the theme rooms are fun. And you can visit the casinos. There is also a nice paddle-wheel steamer cruise on the lake - though it ran aground about 10 minutes into the New Year. (Got towed to the pier, no problem.)
But if you want to find something to do outside, search Groupon for events in your area. Often there are interesting tours, interactive dinners and puzzle events, and lots of other fun stuff you may not know existed.
BTW - 36 years 
Book a B&B in a quaint little town and spend a long weekend exploring it? Suburban Plankton and I went to Mendocino, CA for our 15th anniversary.
How about a hot-air balloon ride?
It can be just the two of you (& the pilot).
These are all great ideas, thanks! And congrats to all you fellow married folks.