Fishing day at a lake in California. Where can i go?

[rmottino]

NOTE: I posted this at Southern California Freshwater Fishing forum too... if moderators think its a dupe please move or delete.

Hello, my name is Roman. I'm from Argentina and i love fishing.
First of all, my english is poor, sorry about that. I hope i can explain myself.

I will be traveling in January 2013 all arround the west coast by car, from San Diego to Los Angeles, Grand Canyon NP, Canyonlands NP, Bryce Canyon NP, Las Vegas, Death Valley NP, Sequoia NP, Yosemite NP and San Francisco.
As a fishing enthusiast i would like to spend a fishing day (or two) at a nice, natural lake.

I intend to rent a paddle boat or a small tracker ( i don't know the options i have ) to find a good spot and spend the day fishing. Shore fishing is also welcome.

I don't want to take a fishing trip or guided tour, just go to a lake, fish, grab a bite and spend a great outdoor day. I don't care the size of the fish (of course biggers are welcome) just to enjoy catching some in a quiet and natural place.

Ok, this is getting long.
The question is, what lake do you suggest? Considering it will be winter. A lake with a place to rent a boat and equipment will be great.
Any suggestion or opinion on my idea is very welcome.

Thanks you very much!
Roman