Re: What is seduction to you?
Gift certificate for a new bra and panties from a lingerie shop. One that will do a proper fitting and make sure she gets the right fit. For the nearly-naked P90... :-)
I don't know about other women, but for me a good fitting new bra goes a long way towards the great 40+ body after 3 kids.
A chick-fit tee shirt and some new workout shorts too.
If she spends a lot of time at gymnastics watching the kids in the evening at classes in a viewing area, one thing I saw that goes a LONG way in the esteem department is to have hubby bring in a nice salad meal and iced coffee from a nearby cafe. Delivered with a kiss on the neck, by your most attractive self. Then ask if there is anything else she wants, such as specific chores done around the house or dinner on the table, errands run, etc. before she gets home.
How it works is that after you leave, there will be many many nice things said about you by the other women...
If you are already doing this and it has fallen short, my condolences.