This is an issue near and dear to my heart. As a DIY/home-recording enthusiast with little-to-no money and hi-fi ambitions (while I occasionally appreciate listening to an indie lo-fi act, I've never wanted to do that myself), I'm constantly learning new ways to do things, and revising what I do know. That and I *know* the mix on the film I just finished is going to be horrible...the rough cut I was given EVERYTHING was maxed out. I had to turn the film audio down 15db just to HEAR the music I was working on.
The problem, at the end of the day, is the mix, not the mastering. Sure, you can EQ a film mix to cut down on some of the noise, but then you end up with a muffled mix. If one actor's voice is too quiet, you could use compression to balance things out, but again, you're upping the total noise floor. When the noise floor comes up, sonic room for music and foley is greatly reduced. So you could master to your heart's content to get a decent mix...or you could take the same amount of time and learn to do ADR and foley well, giving you the control you need to get a balanced mix. That way, everything can be clear at a lower overall volume, giving you plenty of headroom to mess with the dynamics as needed.
The "loudness war" happened(is happening) in music because of the misconception that a listener is going to respond more to a "hotter" song when they here it on the radio. You could blame it on label executives, but independant acts are often just as guilty, since we sometimes feel the need to shout to get noticed, metaphorically. These opinions, by the by, do not take into account genres such as noise or early black metal where it's (often) supposed to be loud and not pretty, therefore an aesthetic choice.
All that said, home mastering will never be as good due to the experience of a good mastering engineer. The tools are available (Waves is pretty awesome. I use Ozone because it's cheaper and you can get good results with it if you take your time) to just about anyone these days, but an engineer has spent years understanding the gear that you are trying to learn as you go.
rockerrockstar, what was it about the mastering that you disliked? Being able to pinpoint what you like and what you don't is an important step in getting better results the next time around. Analogue mixing may have helped you get what you are looking for, if you are going for a specific sound; the thing about analogue gear is that it colors the sound (in a way that we have grown accustomed to, sort of like a tempered scale). It's not necessarily "better" or "worse"...just different, and with the amount of plugins (even free stuff...check out kvraudio if you haven't) designed to emulate what we like about analogue gear, if you have the time to really work it, you can get an "in the box" recording that sounds just as good as any other. Analogue mastering, well, there's a reason mastering grade EQs can set you back 10 grand or more! For demos though, you might consider taking the time to learn the plugins. When mastering, take a recording of a song similar to the sound you want to A/B as you work (never a bad idea to send references to a mastering engineer as well...there are an infinite number of ways a record can sound "good"; it always helps to know what it is you want).
Cool you used Sweetwater, by the by, they're one of my favorite non-local places to buy gear!