I live in Colorado. There are a lot of great trails here, but documentation is hard to find on many of them.

I'd suggest picking from segments of the Colorado Trail. You can buy the guide books and data books at http://www.coloradotrail.org/

Being from low altitude, I'd suggest segment 1 as a start. Given you only have 3 or 4 days, you could do the first 2 or 3 segments. Keep in mind, much of the Colorado Trail still had snow on it in July. Mostly in the higher altitudes.

If you want to take it easy (around 5 miles a day) segment 14 is my favorite, but I haven't seen all the segments.

I'm not familiar with the Ice Lakes Trail. If it's the one in Colorado's Incredible Back Country Trails, it's at 12,500 feet. Chances are at least one of you will have some problems with the altitude. The climb looks real difficult for people not used to higher altitude.

If you can, take an extra couple of days. I could take you on a lower altitude day hike about 50 miles from Pueblo to help you get acclimated without heavy packs. Then from there, you can go to segment 14 of the Colorado Trail. If you have your mind set on a high lake, I'd recommend Goodwin Lake which is about 5 miles SW of Westcliffe. I'm told there is real good fishing there. It's at about 11,200 feet. I've seldom seen other people there. There is plenty of water along the way so you won't have to pack to much. You can see a video here.

While still planning, I'd suggest buying Topo Explorer: Colorado. You can draw maps on it and it will give elevation changes. I use the following approximate scale.

up to 300 feet/mile: Easy
up to 700 feet/mile: Moderate
up to 1000 feet/mile: Difficult
up to 1500 feet/mile: Very Difficult
Anything more: Not for me except for distances under a mile.

Keep in mind, thunderstorms are common here after 1 to 2 pm. It pays to be off exposed areas before then. It also pays to get up and start hiking near sunrise as the best views are in the early morning.

Bring chapstick and start using it before your lips start to crack. Most people new to Colorado seem to have this problem. Drink a lot of water as it's easy to dehydrate. Many people who arrive without a tan tend to burn more easily.

Freezing night time temperatures are common here in July above about 9,000 feet.

My choices are somewhat biased based on what is close to me.