I'm all for tall girls in heels, and I'm a male heel-wearer, too. At 5' 9" and a bit and size 10, I'm lucky to live near the HQ of Magnus Shoes who upply up to size 11 in women's styles.
Mostly I go for ankle boots and I'm probably more comfortable in 2" heels than flats. I go up to about 4" but not for long periods and I only wear courts occasionally. I don't have problems if the shoes or boots fit well; this year's boots are just under 3" heels and I can wear them all day. I have anothe pair of boots with slmost the same height heels and though they look lovely, I can't wear them for as long, so you need to find out how you get on with each pair as it will vary for all sorts of reasons.
If you want to go high, work your way up and choose your shoes carefully so they are comfy in themselves. That way you're only tackling the height, not tight or badly shapes shoes as well.
It does take time and perseverance to wear 5" heels.
Hi im also 5ft 9" I wear heels when clubbing etc but generally dont go above 4" then not exceptionally tall and I cant walk in anything higher, unless they are my 6" sex shoes or boots I wear for oh and me xxx practise around home with wedges to start with then go too heels gradually... I find closed toe heels are more comfortable but I put up with strappy heels for the look. Good luck and embrace your height, most girls would love the long legs that come with our height so show them off with heels xxx even though we wish we were shorter love your assets ;)
Obviously you can go a bit closer to your limits if it's just for the bedroom, but do make sure there's a clear walkway for when you make your stately progress to the bed. Indoors, you have less room to manoeuvre if you do start to topple over, and if the floor is strewn with discarded clothes or kiddies' toys, you need to be VERY careful! And don't forget you have further to go down when you get to the bed and recline - mess that bit up and you'll look drunk, or easy, or both. Mind you, that might suit ...
A couple of practice sessions so you can assess how it's going to go would be a good idea. But in general, just work up to it; most women (give or take problems with joints, etc) can wear a 2" heel all day if it's not too pointy and it's part of a well-fitting shoe. Moving from that to, say, a 3.5 to 4" heel isn't such a leap then.
If your plans include 5" heels and beyond, you need to be comfortable in 3-4" heels first, I'd say. You don't want a trip to A&E in that outfit that seemed so wonderfully slutty and just right for a steamy night in! And it's not sporting to change before you go - A&E staff deserve some entertainment.
If walking in the heels is a real problem you could always do a role play as Cinderella - in comes Prince Charming with the shoe; you sit to try it on; lo! it fits! You stand up, totter over and collapse into his arms, at which point your shabby dress falls off to reveal - well you know what it reveals as well as I do.