I have a magic machine that can put you in any one specific location in the Harry Potter universe. You can’t wander from there.
You can’t be too general, you can’t for instance say Diagon Alley, but you can go to the Leaky Cauldron, or Olivander’s wand shop, or Weasley’s Wizarding Wheezes. You can’t say Hogwarts but you can say Dumbeldore,'s office or the potion’s dungeon or Hagrid’s hut.
The Burrow? Number 4 Privet Drive? The department of mysteries? The quidditch world cup? Azkaban? St. Mungo’s hospital? The Hogwarts express?
Given your rules, there are only a handful of practical options:
Hogwarts. You are blasted by the psychotic wizards who believe it is their right to screw with the minds of anyone else, although you may get to explore before they turn your brains into sushi.
Diagon Alley. Well, it’s fun and people would likely not notice you. You may get some good opportunities fiddling with the gold market, since there’d always be a good way to use currency cornering.
The Ministry of Magic. You could probably ask polite directions to the minister, and then blow the brains out of his secretary and then the man himself. Not much else to do here.
I think I’d just like to hang out in the Griffendor common room. Maybe watch Fred and George play exploding snap, see Hermione study, watch Harry and Ron play wizard’s chess, and maybe see Neville blow something up.
Advanced technology (past about medieval level, it seems) doesn’t work in zones of strong magic, remember?
And while I certainly understand the sentiment behind “Hermione’s bedroom”, just what do you think her reaction would be to someone suddenly appearing in her room without explanation?
Fine. Harry’s bedroom. (Not really, he’s much too young for me.)
Really, send me to the Leaky Cauldron. I could probably blend there better than anywhere else and it’d be nice to have while away a half an hour in the pub.
If not that, then the shop where Harry buys Hedwig.