I do understand I have multiple saves with themes and sometimes I don't play them until something new comes in a pack that makes me say yes! It fits their character just right for the sims anyway....That's happening right now for me I'm all involved in playing and revamping a themed save... actually 2 of them. So then I play that save for awhile, sometimes rotating through characters and changing up their lives, looks and stories thanks to a new pack that really made me want to get in those households. It snowballs then for me and new ideas come or old ideas can be completed and or added in.
Usually I move on to a new save if a new pack comes and it really won't affect my currently played saves... or I even start new saves and stories.
I have found that I go back to older saves most when I have a real fondness for the characters... That's why I use it often as an ongoing fanfiction in the sims universe more often than not. I'm fond of them both because I made them and I'm also fond of that character that I got from other media or created myself.
I try not to feel strange about the way play I realize it's my own way and as long as it's enjoyable to me that's all that counts. I get tired of playing all the games I own from time to time including this one. I just do something else until it's sim time again.
Really I think that magic ingredient is a creative spark and you have it... you just burn out a little when you hit the daily grind maybe. Rotating helps or just doing something else that isn't sims if it comes right down to it. It refreshes eventually so my advise is to not throw out anything you made with great passion.