as someone pointed out, i'm thinking more along the line of, say, 75 to 150 people over the course of a day, with various things going on throughout the day that would bring in different cohorts. i don't know if that's practical. but, you might have a schedule of events, and some of these take place outside. so, here's a sample...

1. bring your bike in, get it washed and lubed by the WD40 or ProGold tech reps, they show you how to do it right, and they offer packs of their products at a good discount on-site. so that's outside, during the day.
2. also during the day there's a lunch BBQ.
3. there are bike fittings going on all day long.
4. there are sales going on all day long. maybe a number of manufacturers decide these are great opportunities to get rid or last season's stuff.
5. throughout the afternoon and evening more lectures and personal appearances. i haven't spoken to any companies, but i would expect there would be a number of them, so, you have roka, specialized, QR, felt, orbea, blueseventy, and so forth, and they'd bring in some of their pro athletes.
6. maybe the day starts with a bike ride and the pro athletes are on the ride. maybe a ride and a run, from the shop.
7. evening, there's a raffle.
8. clinics throughout the day on how bikes, wetsuits, etc., compare. so, if you're looking for a wetsuit, and i mean if YOU are looking, which of the wetsuits the store sells is the best for you. likewise bike, etc. and how to go about properly choosing.
9. each store will have a lot of manufacturer's reps in the store, all day long, so if you're interested in a QR or an Orbea the rep will be in the store, you can talk to him.
10. the event will be free, but:
A. there will be a cost for the food
B. we'll raffle big things, but there'll be a cost for the raffle. raffle tickets would, i think, be sold in advance of the event, because some of the raffle winners will be those who get fit on that day. the fits going on all day long will be fits won during the raffle. and, if possible, the bike, wetsuit, etc., won during the raffle will be picked up on the day of the event, with the braintrust there to help pick out the wetsuit, fit the customer to the bike, etc.

maybe something like that.