Hi Vroom... OK... one great flat ride is the Silver Strand on Coronado. It's 15 miles out and 15 back if I recall... there is a loop you can do around the island as well... great places to stop for lunch etc... it you ride there be SURE to visit Hotel Del Coronado. Very famous... it's where the President stays when he's in town (no matter who Pres is!) and the Christmas display is amazing.

Fiesta Island is also a regular ride spot for many... not sure how far it is all the way around, but you have a view of the water no matter which way ya go... I think you could extend it by doing several loops.

from where your staying, which is an area called Point Loma, you could also go up to Cabrillo National Monument. This would involve some climbing, but nothing steep... just a few miles of it...

I still think the coast is one of the best rides... if you avoid N Torrey Pines Rd, the climbing is very minimal, there are TONS of other cyclists at any given time on the road there, and lots of places to eat. There's something fun about riding along and watching the surfers catch waves...

It's stayed warm very late... still in the 80's! So heaven only knows what Dec will bring...