Base in NJ
 

I have to spend 3-4 days attending to some stuff in NJ, specifically Somerville, Manalapan and Newark. I'm budgeting a day in each but need to be flexible in case things happen quicker/slower than expected.

What's a good base? Nothing fancy. Convenient & safe will do.

I'll be coming from either NYC or CT. Where should I pick up a car?

To be in the best spot to hit all three, I'd say you want to be around Woodbridge. If I were you I'd take Amtrak/NJT to Metropark (Iselin) and get the car there.

Good thing you are not looking for anything fancy, because you're unlikely to get it in that area of NJ :)