きものをきたらどうですか？ -Does this mean "why not wear clothing?" or perhaps "What about the clothes I'm wearing?" I'm not quite sure of the meaning.

Also, how would you say "Why don't you go see a doctor?" "お医者さんに会ったらいいでしょう？”　or maybe, ”お医者さんと一緒に話したらいいですか？”

And, how would you say "I want to get into better shape"? like more physically fit.

何を着ていったらいいですか？-Just as a note, I figured out this sentence when I typed it because the Kanji popped up. haha I love Kanji SO MUCH!

Thank you in advance!

Spencer

How about wearing a kimono?
How about if I/you... wear(s) a kimono?

The どうですか at the end of your first sentence means "How is it?" or "How will/would it be?" and is used to make suggestions, so you could use that for your second sentence:
医者さんに行ったらどうですか。
Or, if you want something stronger ("You should go see a dcotor") you could say 医者さんに行ったほうがいいです。

I'll leave the fitness sentence for someone else - I could convey the meaning, but I expect someone less physically lazy than me will have learnt a better way to say it ;)

いいですか - as in your last sentence - is asking for advice or permission (or asking whether someone/something is okay), rather than making a suggestion.