I have no experience east of Oneida Lake. If you do go west of Syracuse I can offer some input.
My C28 is currently in Brewerton. (Brewerton boat Yard is great). The original plan for this summer was the triangle loop in 2 stages, but with the high water issues on Ontario and in the seaway we scrapped that and did our first 2 week stint as a canal / fingerlake trip from Brewerton West to Seneca and Cayuga Lakes, and back. It was a GREAT trip. We spent nights in Brewerton, Baldwinsville, Seneca Falls (twice), Sampson State park (east shore of Seneca lake), Watkins Glen (2 days), and Ithaca (3 days). In all locations we had very reasonably priced (FREE at Seneca Falls) dockage and very nice facilities.
Baldwinsville is a great place to overnight on the southwest side of the lock. No marinas though, just a portacan. Try Danni's for dinner and B'ville diner for breakfast. Seneca Falls is worth the cruise even if you don't have enough time to go further - 33 miles between locks with some higher speed cruising sections. GREAT boater's amenity building - free bath / showers, and low cost laundry. Plan a couple of nights, and spend an hour in the museum. You can stop along the way in Cross Lake, a nice place to stop for a swim. no facilities that I could tell though.
If you go that far, make sure you have enough diesel to go down to Watkins Glen and back without refueling in Seneca Lake. We stayed at the Village dock marina, a great location. The one diesel location at the south end is old and VERY expensive. On Cayuga lake, the marina in Lansing (southeast shore) isn't so bad. You can walk all over Watkins Glen. Plenty of places to eat and drink. Don't miss the State Park falls and Tobey's donut shop for breakfast. A day touring the wine country is a lot of fun.
Ithaca, on the south end of Cayuga Lake, is a good sized town with a great downtown scene, the commons (a taxi or bike ride). The Treman state park marina is very nice and reasonably priced. The Boatyard restaurant / bar is a must. A good farmer's market nearby on the weekends. Our fold-up bikes came in real handy, great trails to get you around town.
I'm headed back in another week or so for a couple more weeks on the boat. As far as I can tell, the St. Lawrence is still a mess so might head east on the canal at least to Utica and back, not sure what to expect. I'll plan an overnight each way at Sylvan Beach on the east end of Oneida Lake. Maybe we'll pass some of you on this thread!