L.C.
My husband was the one home with my son most of the time (he was in day care a couple of times a week). I know my husband would try to include my son in some of the chores he did so they could do them together - food shopping, gardening, folding laundry, etc. At some point my husband would tell my son he had to do some work and my son would play on his own in his playroom and maybe watch some tv or video. When my husband was finished they would play games together. A couple of times a week they would go to the zoo or the aquarium or the place with the jumpers or have a play date.
It sounds like you're doing a lot with your daughter so you shouldn't feel guilty if you need some time to do some things. It gives your daughter the opportunity to learn to play on her own.
When I get home from work, I give my son all my attention until I put him to sleep - I feel guilty because since he was 2 months old I have never been home with him! He's almost 8 years old and he keeps asking me when I'm going to stop working. You're lucky you have the summers with her but you still need to have time to do your own things.
Hope this helps!