Seems to me that this is not just your decision...This is a significant chunk of change your going to drop on this hobby of yours and you both need to be bought into the decision.
You want an 8, she wants a 10..the halfway point is the 7..Actually I have a 7a.
That gets her the side by side seating which maybe just a placebo to you but to her it maybe the difference between life and death...My Wife likes access to full controls so she has at least a fighting chance if I croak.
The 7 (a) is very good airplane, sure is a few knots slower and won't roll quite as fast, but to my mind for cross country travel it offers better utility as the sandwiches are available in flight plus you get the bigger instrument panel and the Wife can hold the approach plate in front of your face for those SLIGHTLY stressful IFR moments near the ground.
Now yes there are those superhumans that are comfortable flying flying an 8 in IMC...I prefer to at least have the seat (passengers lap) next to me for working room.
If aerobatics are your thing and the roll rate is a concern have a look at my videos and ask yourself "if this is all this plane will do acro wise is it enough?"
www.youtube.com/user/frankhinde
If your coming from a C150 everyone of the stable will blow your mind..They are all twice as fast for about the same fuel consumption.
Purely personally you have really got to want an 8 or 10 to have one, whereas a 7 is a better all round airplane.
But be honest here...you want an 8 cus it looks cooler don't you...
Frank