I have done RMI's 3 day summit program and thought they did a fantastic job. Really, the summit day is to climb 4000+' from camp muir, then go all the way down to paradise in one day, getting off the upper mountain before the afternoon sun makes the glaciers too unsafe. So they do make you hustle on that program which I view as a good thing. In fact there are some areas that are quite dangerous and speed = safety in these regions (rockfall areas). They were always polite & professional in my experience. I have taken the 6 day glacier class on Mt Baker with Alpine Ascents International and also rate them as excellent. Both companies set very high standards for their guides and it shows. I have done 2 more trips with Alpine Ascents since then and if or when I return to Rainier I will likely look to them first. The 3rd company getting a large share of Rainier access that I am aware of is International Mountain Guides owned by George Dunn, Phil Ershler and Eric Simonson. I have no experience taking trips with this company but they are an RMI spin off and I get the feeling they will also do an outstanding job. In fact, George Dunn was a lead guide on one of my Rainier trips with RMI I did, I was very impressed with him, very good guide. Net: Find one that fits your schedule and which program looks best for you & your friend, I think you will be pleased with any of these three.
If your goal is really variety, consider taking your glacier training on another mountain, Mt Baker perhaps. Alpine Ascents & IMG runs these classes in Alaska. Yamnuska in the Canadian Rockies and Alpine club of Canada runs these classes in the Canadian Rockies. Google these comanies and visit there web sites.