I don't buy frozen dinners specifically because of the sodium. I have high blood pressure and stroke history in my family, so I try to keep my sodium lower than MFP suggests. That being said, I DO typically cook with the expectation of it lasting 2-3 days. We take leftovers for lunch and have a Hodge Podge night once or twice a week. This being the case, the leftovers MUST taste as good, if not better, than the original. I found over the years that the problem isn't so much the taste of the leftovers, but the texture. To conquer this, I altered how I reheated them.

Basically all my soft, mushy stuff likes soups and veggies get reheated in the microwave; it's fast and easy. However, things that require a bit of a crisp to enjoy (like fried chicken) get retoasted in my toaster oven or the regular oven. 10 minutes on 350 or 400, then a minute or two on broil bring it right back up to par. If you doing something like steak or roast where the importance isn't crispness, but moistness, I wrap the meat in a damp paper towel before reheating in the microwave. This technique is also awesome for slightly stale bread.

In terms of how I cook for leftovers, anything that includes noodles and sauce, I keep the sauce separate and only make enough noodles for one meal. If I want to eat the leftovers, I create fresh noodles in the morning before work. I also try to stick with dishes that taste better over time, like meatloafs and stews because the seasoning seems to really mature by day 2 or 3. But honestly, just with the reheating changes, it's revitalized fried pork chops, pizza, and even fries and onion rings (not that I eat those anymore *choking on lies*).

If you want specifics of my seasoning and stuff, let me know!