Here's a product I love for parties and events - huge mylar balloons shaped like numbers or letters. I've used them for many things (more pictures to come - a NYE Party, Anniversary, I'm sure something else...) and here we used them to spell out "OSCARS" for the Roseville Women of Today's Oscar Party Fundraiser - they really make an impact and come in shiny metallic colors. You can get a few numbers (like the current year) at most party stores, but I generally go to M&N International for ease of ordering and the full selection. Of course, then you have to fill them up yourself, but renting a helium tank is fairly easy and balloons are a reasonably priced decorative tool - they cover a large area and come in all shapes, sizes, and colors.
One thing to keep in mind if you are doing a ton of balloons - tying balloons hurts. Sure, the first few are fine, and I'm pretty fast & dexterous actually, but after a few dozen and for sure as you close in on 1-200, you'll be bruised and blistered. I've never tried the clips, but I might consider that for any future balloon-heavy events.