east. the lakes you want to tour are (as garbageguy said) Seneca, and Cayuga.... there is a canal connecting both of those together on the north end.. Both lakes are beautiful!! I think the other one that connects to Erie is Onieda Lake,, that's north of Syracuse NY,, stay out of that one......its shallow, and frankly not much to look at, the terrain around it is flat and unappealing. Seneca and Cayuga being glacier lakes have awesome views. I have been on Seneca and Cayuga a bunch,, if your into fishing,,, they are both outstanding, with that said, I'd give the nod to Seneca Lake for fishing,, as to boat friendly? any of the Finger Lakes are very boat friendly, they are very deep glacier lakes,, they literally will go from bank shore to 100 ft deep in less than 100 ft from shore in spots.... Cayuga and Seneca both are 400-600 ft in depth in spots, they both have large park/hard ramp launches on the north end of each lake... google it up, there's a listing of launch sites on the NYS DEC site.. if you want to take another trip to another one of the Finger Lakes, go to Skaneateles Lake. no joke, the water clarity is amazing.. it's the most beautiful finger lake in the state in my view...snorkeling is awesome, swim with the fish!,, it's like being in a pool...there is a public dock at the north end, tie up walk into town and get a bite to eat,,, it's awesome, ..it's not connected to Cayuga or Seneca, it's land locked....Pres Clinton summer vacationed there (Skaneateles),, the homes around the lake are awesome. I drag my boat up there bout 10 times per summer....my favorite finger lake.. have fun and enjoy the NYS Finger Lakes!
as to how much time,, both Seneca and Cayuga are 30+ miles long, generally anywhere from 1-3 miles wide... drop into Seneca first out of the Erie Canal, prob take a few days to get around it,, then out the canal to Cayuga... you could probably get the whole thing done nicely in a week... taking your time... both parks at the north end of each lake are state parks and offer over night slips if u want....
have fun!! God scratched the ground with his hand in Upstate NY,, wow!! a boaters paradise up there,,, Im glad Im only 1 hr away from most of em