Thanks for all the suggestions! I'm trying to buy my ticket now and have one more question:

It seems I have two routing options from YEG to LGA. As mentioned, I'll be very tight on time when arriving into LGA. Both the routings get me into LGA at the same time (the earliest I could find) -- but which would be the more reliable choice?

1. YEG-DEN-LGA (1 hr connection) (operated by United Express/Shuttle America, then UA) (dept 6:10 am)

or

2. YEG-YYZ-LGA (2 1/2 hr connection) (operated by Air Canada, then AC Jazz)
(dept 6am)

I assume choice #2 is better since it gives me more connection time (2hr vs 1hr, since a shorter route), even though I'd have to go through immigration (at YYZ, while with choice #1 I'd be doing it before I leave at YEG)?

thanks for the help

edit.. just want to add: I'll have one checked bag. No Nexus or GE.