I've hiked extensively in the front range (norther part) for reasons of geographic convenience--can't comment on the other options pointed out in the thread.
The front range is of course overrun with tourons but it's easy to avoid the worst crowds by starting early (before sunrise) which is smart in any case because of almost-daily t-storms in the summer. Trail Ridge Road an amazing drive a half hour before sunrise and hell to drive after 10AM or so, for example. In most years, there will still be a fair amount of snow above 9000' into early June, even in the drier, eastern-most points. Above treeline (>11,200' typically) and off trail can be much better going that time of the year since snow drifts into lower areas and treeless expanses of snow melt sooner (or at least compacts into a firm surface) compared to snow in forested areas. Snow can be annoying but I actually enjoy hiking in May/June because of the added challenge and the fun of glissading back down.
In RMNP, the Mummy Range holds less snow and is somewhat less crowded due to long summit approaches than Bear Lake. Having said that, there are islands of obscurity and some amazing places around in and around RMNP.