This article has lots of good info for your lawn care:

http://communities.canada.com/vancouversun/blogs/inthegarden/archive/2009/03/20/your-guide-to-basic-spring-lawn-care.aspx

If it was my garden this is what I would do:
1.control moles you don't want them
2.Put some compost/soil in the lower areas you can mix some sand in especially if you have moss.
3.I would try to make it even first with one year and no moles
4.Then you will have a good idea how it worked.
5.Fertilizer may also help.

Aerating won't do anything to help level out the existing lawn but it will help to improve its health and that may be just as valuable. Soils under lawns are compacted because we walk or play on them constantly, push heavy equipment around on them and water them frequently. Once compacted, the soil no longer has sufficient air pockets to provide oxygen to plant roots or allow percolation of water down into the soil levels and it doesn't retain nutrients. Soil biology is disrupted as well. The result is that plant roots do not penetrate very deeply and you wind up with a sparse, patchy lawn that is intolerant to drought, unable to access nutrients easily (even when fertilized) and unable to outcompete weed or moss development.

Annual or at least regular aeration is pretty much SOP for good lawn care and I wouldn't recommend overlooking it just for economic reasons. Sure, you can get by without it and just level your lawn by filling in the indentations and overseeding but you will NOT get the same kind of results and will continue to have problems with a patchy lawn, weeds and irrigation runoff. It's worth the investment to rent an aerator (or hire someone who does this) if you want a good, healthy lawn.

If you have kids or dogs running around on the lawn, it needs annual aerating, for all the reasons gardengal gives above. If you just walk on it once a week to get to the back flower bed to weed, then you don't need to do it every year.

The moles, and the burrowing insects they're chasing down, are doing some aerating for you, but not in a very systematic way.

The usual method of leveling a lawn consists of adding an inch or two of topsoil to the low spots and then waiting for the grass to grow back up through it before adding some more. This is usually done in yearly installments. You could add however much soil it takes all at once if you then reseed on top of the new soil. If you till the bad spots before adding soil, the tilled soil is going to settle again and you'll have low spots again. Lawn seed beds are rolled and compacted slightly before seeding to reduce uneven settling.

When your aerate, you can rake up the plugs from the high spots and use those to help fill in the low spots.

Aeration before summer really helps with water penetration when you need it later in the summer.

Sorry about your job, I've been in the same boat. It does give more time to work in the garden though. Good luck.

hvaldez - That's my plan too! I just need to kill and rake up all this moss, and track down some clover seed before having my yards aerated.