noob needs help from the wheel gurus

What's up everyone,
I'm new to the site and was hoping to get some help.
I searched for some answers already but couldn't seem to find anything specific to what I need.

I'm about to spend a nice chunk of change on some wheels so i'd like to get the specs right before I do so.  I have an 06 GS300 on tanabe sustec pro 5's.
I'm new to the game but i'd like to go vip style with a somewhat flush fitment.
The car will be a daily but my work is only 3 miles from home.  If I had to choose i'd still like something moderate agressive but something i can still drive some distance on if need be.  I also don't mind doing some shaving on the fenders if need be.
Lastly, I'd like to roll on the coilovers for now and go as low as I can for now. maybe air in the future.

the specs i'm looking at now are 20x9.5 +26 (standard disk) F
20x10.5 +25 (low disk) R

Can anyone help me with suggestions from experience? Will this be pretty close
to flush  and will I be able to achieve what i'm looking for from what i mentioned?
If so what tire size would be right and would I be going 30 or 35 series etc?
BTW why do some people go different height of tire in the front compared to the rear?  any help would be much appreciated and i apologize in advance if this is a worn down topic.  thanks

i have some 19x9.5 19x11 +19 +20 work equips that will be moderate

how much are you going to spend and what are the wheels?

Looking to go 20's.
leon ordens
thanks anyways