My son gave up naps at three. I didn't enforce "quiet time" as he was too full of energy. I just went with the flow.
I got a lot done a little bit here and there during the day so by the time they went to bed I had "me time". I also made a deal with him that since he gave up naps he had an earlier bedtime. Last year he was in bed by 6:50! Every single night and he was tired! He sleeps until 7am so it was nice.
I got time with my older daughter and she was in bed back then at 7:45.
Now they are 4 and 7 my youngest is in bed by 7:30 and my daughter by 8:15ish. It is nice having one on one with each of them at some point during the day.
Your kids will outgrow the endless energy at some point. Last winter my son kind of mellowed out, found playing by himself was fun and I do babysit a few younger boys, so some days he has a friend here to play with. He is so into his action figures, puzzles, playdough or whatever I really don't struggle with keeping him busy. I make sure he gets outside to play for a bit and burn off steam each day! :)
I also got him in a few days a week in preschool last year and this year he is in Pre K. He loves school!!
I suggest if you really need that downtime during the day you put them in a one or two day a week preschool. Giving you a break to get errands ran, relax or whatever.
If you are feeling really tired at the end of the day, maybe making bedtime a little earlier for you too! Everything doesn't have to be done in one day, so if you are tired when they go to bed, just sit down and relax. Good luck!