i'm glad you're posting and getting such good advice. think everything ASBS told you is absolutely right regarding adopting a TB, one thing i would chime in about a TB is that they are normally BIG horses, and for an inexperienced rider, that can be a little intimidating. it may sound funny or odd, but i've learned that much of horse riding is mental, and if you feel intimidated or scared, it can potentially affect the horse's frame of mind too. again, this may sound silly, but some of those TB's get so darn tall, you'll feel like you're 10 feet off the ground!
if you're in washington state, there should be some cattle ranches around your area, try to find a 10 year old (or older) ranch gelding who's been up and down and all over the place, a horse like that will take care of you and tolerate your mistakes - and every rider makes mistakes.
Here are a few examples of horses on this site that i'd suggest for someone in your situation. i'm not recommending these horses specifically, just saying that these horses have some of the attributes you should look for
Again, i'm not suggesting you buy any of these horses, in fact two of them are from iowa, so i'd guess they won't work for you!
but this gives you a good idea of a horse that will probably work for you. you'll never regret taking a nice quiet ride on a level headed horse.
as far as shoeing, it's my guess that in your part of the world, shoes are going to be pretty necessary. when you do get your horse, first time a farrier comes to work with your horse, be there and talk with them and watch how they work and treat your horse. if you don't like it, find a new one.
lastly (and i know i'm really starting to ramble here), i think about the most important advice you can get is - don't have the mentality that you are going to be your horse's best friend
. the safest, best relationship with a horse is one of trust and respect and if they don't trust and respect you, you won't get as much out of them as you can. if you treat a horse like you would a dog and treat it too kindly and spoil it, it can have very dangerous consequences. i'm not saying you have to be mean to your horse, but you do have to be firm. simply being kind to your horse won't convince the horse to be good to you, their brains don't operate that way. don't ever let it push you around or dictate what you do either on the ground or in the saddle. you can have a respectful, well trained horse that is still a best friend, but you can't be a horse's best friend unless you do have that respect from them. make sense?