03 Cavaliers have a nice body style, there's also a lot of aftermarket accessories for this model. But if you just want to keep it running smooth, Id suggest changing out the spark plugs to a set of AC/Delco Rapid-fire plugs. Also changing out the Air filter for a K&N brand filter.
Rapid-fire sparkplugs are high performance plugs that gives your engine the best spark for a more cleaner burn of the fuel which translates to more horsepower and a cleaner inside of the engine.
K&N filters provides your engine with more volume of air with no effort from your engine having to suck in air. Allows for better gas milage and more horsepower.
Since you "love (yours) to pieces", I won't elaborate on my dislike of them. I've known people who've owned them, and I guess one of them was satisfied with his, and maybe they're worth the money they paid for them, but, since it's a GM product, I can't see how. I hate to go on about my dislike about a car you own since I know I don't like people "bad mouthing" a car I purchased with my hard-earned money, so I'll just leave it at that. I do hope you get over a hundred thousand miles on it, with at least 35 mpg and the most minimal car maintenance and repair costs, and accident free. In the days where cars continually cost more, and the price to drive them increases as well, we all need the best we can get. God Bless you.
I owned a 1988 and 1994 and enjoyed them. Cavaliers have issues with sensors failing at about 50K and the 94 needed a new alternator at about 60K, but nothing real major. I think it is a good car at a reasonable price.