Lets say I have 12 recessed lights, and two receptacles. If I had all of the lights on, with 100 watt bulbs, on at the same time. And a TV on one of the outlets. Would 14/2 wg and 15 amp breaker be good enough or should I go with 12/2 and 20 amp breaker?
Thanks

I'll leave you with this:

Probably 100W is too big for the fixture. Check that.

Next Amps = Watts/Volts, so in your example

12 lights * 100 W per light/120 Volts = 10 Amps

TV is unknown, but likely less than 200 W.

You should size a circuit at 125% of it's rated capacity if the loads are expected to be on for more than 3 hrs at a time.

The lights are an iffy situation.

I'd go with 12/2 and 20A

I = ((12*100)+200)/120 * 1.25; size up and I'll bet you'll get 20A

Well, a 15A 120v circuit can handle 1800 watts, so I think you are fine with that.
I bet the TV isn't more than 300-400 watts.