those using logic pro 9/x

There are some basic presets on the master channel for final mix-downs which will populate a bunch of mastering plugins for you. You can try starting with those for basic overall compression, etc., and modify to something that sounds good to you. No reason NOT to have normalize clicked from my point of view, but I'm a super amateur as well.

 

You say the volume goes down when you normalize the volume. But doesn't that depend on how hot the track was to start with. Some tracks would get louder when normalized. I think your observation says more about your tracks then about anything else.

Maybe if all yours move down you are recording with more gain than you need

It's all relative and the actually volume depends on the knob on the front of your headphone amplifier.

 

What do you mean by "mix"? Are you talking about making a dj mix or mixing down a track like post production?

Either way, it seems like you're volume is just low on the mix. You can just raise the volume without clipping. If it's real low, logic's limiter can boost your signal, just don't go into the red. -6 would be perfectly acceptable.

 

the Normalize function is "on" by default in Logic Pro 9. Unclick it before you bounce the track. I'm presuming of course, that your mixing levels are all within acceptable ranges for both the lows & the highs.