You shouldn't need pitch correction and IMHO sonic maximizers sound dreadful ! If you miss a harmony, and it is a one off, well no one will walk out. If you miss the same one all the time, then change it. Knowing your range and being able to hear on stage should be all you need.

If you have a nice analogue desk / power amp / speakers / monitors, Id go with an Alesis midiverb or similar. I have one and it is very easy to use and great for vocal verbs.

A cheap compressor or two is also a good idea to tighten up drum sound / vocals. If it for live work it doesn't need to be expensive.