The first route is fine; you need have no apprehension about NY149, US4, VT22A, or US7. Those are state and US highways, and suitable for large vehicles (and indeed used by regional truckers, etc. along with the rest of us). 149 through the outlet shops in Lake George can be a bit congested and slow going, but it's not a long stretch of road at all. There are some rolling hills but no extremely steep or long grades, nor nasty switchbacks. Do take care in Albany to continue on I-87 north rather than I-90; it's a bit of a messy intersection there, but decently well enough marked.
The Garden State Parkway is fine (and legal) for RVs, unlike pretty much every other parkway in the area. There are some lowish clearances in the far right lane. I-287 is an alternative that is perfectly workable, though it's a little longer and in rougher condition, as I understand things.
Avoid I-95 over the GWB at all costs; I-95 through the heart of New York City is no fun at all and can be pretty slow going at the wrong time of day. I-287 to the Tappan Zee, and then either I-687 to I-84 to I-91 or I-95 to I-91, and thence I-91 to I-89, is a bit better but still can be busy and slow and I think is longer than the first route with no particular advantages.
For planning purposes, it's just about three hours from Albany to Burlington, maybe a little more in a motorhome. It's usually around four or four and a half hours from New Haven, CT to Burlington.