I use different setups for different situations - street and street park, flow park, bowls, townie. Townie is by necessity a different board, but if pressed I could skate my middle-ground board (8.3 twin tail, ML 8.38 trucks, 55mm 101 F4) everywhere - although I would probably put 53mm STF v2 shape on if it was my only board.
If I am doing anything flippy I like an 8", currently with Thunders and 51mm STF. I land more often with this. I could flip an 8.3, but this is easier.
In a bigger bowl I like a longer wheelbase than the 14.4 of my twin tail. I usually use a 15, but I'd like to try a 14.75. I could skate the twin tail, but its so different an environment that it doesn't really effect my skating on either.
When I skate mini ramp I can use any of the setups, but usually gravitate towards the 8 just because the two I skate most often also have a street area next to them and I will probably be trying some flippy stuff there.
I also have a few other setups built just because I had a bunch of decks, trucks and wheels leftover that I tried and they weren't my first choice. They don't really get skated and just take up space in the garage.