I've rescheduled my trip (actually several back-to-back trips) to start August 1. We'll see what happens! Yes, I expect the mosquitoes to be late, too. I just hope enough snow will be melted that the creeks (especially Pole Creek) won't be too high--I'm short and have a dog who refuses to swim, so I will have to change plans and retreat if I can't get across.
If you don't have time for the entire length (plus a lot of scenic side trips you shouldn't miss) of the Fremont/Highline trail, then start in the middle, at Elkhart Park. You can do a loop with the Seneca Lake and Pole Creek trails so that only the first/last 5 miles will be a repeat. You can go in on the Seneca Lake trail, quickly hit the scenic highlights like Titcomb and Indian Basins, then go south away from the crowds. South of Pole Creek, there are two north-south trails, the Fremont (route of the CDT) and Highline, with a number of connecting trails--you can do as long or as short a loop as you want, or a bunch of figure 8's. If you're going up on the crest, there are plenty of off-trail routes up there, some of which involve glacier travel needing the appropriate gear and skills. With 5 days, maybe as far as the Golden Lakes and back on the Fremont Trail.
Re bears, I'm told black bears are also in a camp-raiding mode in the Golden Lakes area. North of (approximately) Pole Creek, you're required either to hang your food or to use a canister--this because the grizzly bears are moving south.
David, being from NYC, you may very easily have an altitude problem. Even if you don't get AMS, you will get very tired very easily! Starting at Green River Lakes, where the ascent is gradual (not much climbing the first 11 miles), will help. Unfortunately that means a couple of days hiking through mostly bark-beetle-killed forest, although there are plenty of views of Squaretop and other mountains to liven things up. Planning short, easy days your first few days will help, too. I wouldn't try to do the whole length in 5 days unless you're previously acclimatized!