I would agree on Thai Monkey Club and US Thai. (Although, I like Edgewater, US Tain restaurant is a little rough and basic, but food is good).
Honestly the local Thai Basil 'chain' (I guess about 5 Denver locations) is also quite good, but tuned more for American 'foodie' tastes (but they will properly do orders for Thai style and heat).
Also consider Jaya Grill near I25/Colorado, which is Indonesian, Mayla and Singaporean ... and very hot!