Thanks all,
I don't like spindly tires because I don't feel like I am getting a confident grip on the bike.
I agree with all of you: Use the marin I have with some upgrades and take it from there.
I'd be coming here for more advice here. My two main grips with marin right now:
1) Painful seat ( I have bony butt )==> any advise for good saddle ?
2) Handle position not too comfortable..==> any advise for good bar ?

Thanks again!!

I wish i can get rid of my car if not altogether but to a larger extent, we have two cars in the family..