Bacchus,
Good answer. Are there marinas that cater to loopers, and it there a thought of being a bit south for milder winters, like KY, GA, NC, SC.
Seevee
I'll qualify my answer before proceeding - am not a looper but have traveled NY & Canadian canals, Lk Ontario, Lk Champlain & St Lawrence often. Lots of great cruising in those areas. I have spoken to many loopers at our home port on Seneca Lk (NY Finger Lakes) and while cruising.
I would say...
There are good & not so good marinas / yards most everywhere
I am not aware of any that "cater" to loopers
I'd say looking for a good marina would be secondary to figuring out where you want to be or plan to be at / near the end of a season and then to look for recommendations for a good marina/yard
Further south may be an advantage - but depends - if a season cruising will put you there but not so good if it's not that far from home port. NY canals typically open approx may 1st but will depend on winter run-off & spring rains...also the Hudson can be a little treacherous during spring hi water due to lots of logs/debris.
Several cruisers I have spoken to have left there boat at Brewerton, NY - there are a couple of good choices there (from others experience & recommendations) Winter Hbr has indoor heated storage - not inexpensive but an advantage if you wan to do any work while on the hard. EssKay yards is another I have done some business with and others have spoken about.
Brewerton is close to Syracuse and an advantage if you would be flying in/out.
If driving there are other very good yards not too far away.
Brewerton is also a good location in that you are close to the canal junction at 3 Rivers where you can head W to explore the Finger Lakes, or go all the way to Buffalo & Lk Erie or you can head N to Oswego to get to St Lawrence, 1,000 Is, Rideau Canal, Trent Severn canal, or do a seasons worth of cruising a small loop through most of the above plus Chambly canal to Lk Champlain, & back to Albany & Brewerton
Some loopers I've talked to have completed the loop and returned to explore the areas above in a more leisurely pace...one i met this season was from Tampa and has left there boat at Brewerton 3 winters to return and explore addn'l areas.
If you will end a season on Georgian Bay Lk Huron I would strongly recommend considering South bay Cove Marina in Honey hbr- I've stayed there when we cruised the Trent Severn Canal and it is the nicest marina I have ever been in. We are considering moving there for a season to explore Georgian Bay & N Channel.
There are a couple of "Looper" groups that should be able to provide more first hand info / opinions. Probably worth connecting with them when you start to do some serious planning.
Happy to provide more info based on your specific situation or desires