FI and I are going to be legally married at city hall, and then have a symbolic marriage in RM. Personally, I see a lot of advantages in the sense that we don't have to worry about any mess-ups with paperwork, no need for blood tests (ick!), etc.
That being said, we aren't lying to our families. We aren't advertising anything, but if they ask we'll tell them. We are making it an absolute no big deal. Not even going so far as to have dinner, etc. Its a formality - NOT our wedding.
That solves a variety of your issues. But I can understand not wanting to go that route either. That's a personal decision and while there are lots of threads with this theme that can give you insight into other people's decisions, ultimately it is about what you want.
Now, on the cost front, there are a variety of things I can suggest. First, enlist the help of a good TA. They have so much more bargaining power than you do and they can keep costs (particularly rooms) down. I believe Tammy (host) does this, and everyone loves her. I have my own who I can only rave about. If you'd like her info, PM me and I'll forward it your way.
Other options - call a few other hotels. There are some really affordable ones. Then use the chance that you'll switch as leverage. But seriously? Call them - makes all the difference - you're now a voice with a personality, not just words on a screen.
Hope that helps. And good luck!!!