Jeff,
As Troy said, different mountains require different gear. As for Mt. Rainier, people have asked me what I took up the mountain with me last year; I've guided each of them to the Rainier Mountaineering Inc. (RMI) rmiguides.com website, they have an excellent gear list put together that they reccommend for each of their climbs. Here's a the web address to their gear list I used,
http://www.rmiguides.com/rainier/?id=8#equipment
As for the items on the list, I printed the list out and took it to the store with me and would try the items on to make sure they fit right, and to see if they were warm enough. Then, instead of paying retail for everything, I went to a website called Spadout.com and entered the item into their search engine; I saved an enormous amount of money on gear. If you have the time to wait for the shipping before your next trip, it's definitely the way to go.
I have a Whitney gear list that I created when I took some friends up in September; I'll E-mail it to you.
Take care and be safe,
Ryan Hunt