Yeah, absolutely. I wouldn't advise dipping into the Rookie races but you can absolutely race anywhere you're qualified to run.
I'm the type of racer that can't hop around like that. I have to really get dialed into a car (and even a track) to rise to even mediocre ranks. My last stint with iRacing I knuckled down and only ran the SRF, both in the official series and in a league. It cost me a ton of SR and even dropped me one or two licenses.
Cam, if you ever get into SRF I highly recommend joining SRF Weekend Warriors. It doesn't cost anything extra and it's a great group of racers to compete with. Serious, but not serious bizness. League races do not affect your SR or iRating. And it's a broadcast league with adds a whole new layer of fun to it. They generally race the same schedule as the official series so you don't have to practice two places a week.