I have an 8-month old kitten that sometimes behaves similarly when I get home (I also live on my own and am out at work during the day). Instead of having one long play session, try splitting them up into shorter 15-20 minute sessions. Maybe one when you get home, and one before bedtime, followed by treats - I think I may have read the same book sugarcatmom did
Although cats may often have a 'favourite' toy (mine doesn't, really - he likes shiny new play things), variety is the spice of life! Instead of having a bunch of toys out in the open all the time, keep some of them hidden and only bring them out for certain play sessions. Also see if there's anything you can do to 'spice up' your cat's environment when you're away i.e. using puzzle feeders, or maybe place a multi-level cat perch by a window; anything that keeps your cat engaged and stimulated.
Being a relatively new pet owner, I run into similar challenges, especially in the small space I have to work with. After all, I would like my home to resemble a human dwelling and not look like it's a feline hotel.
If another cat is out of the question, I also echo the suggestion of giving fostering another cat a try, and see how that works out.
Having gone from 4 cats to two (long story), I can say from experience that more cats doesn't automatically translate to more work/problems, and vice versa. If the cats get along, having two cats can be quite beneficial.