If it were me, I would lay out every single SIGNED offer on the table and review ALL of the terms on all of the offers. It's all talk unless it's in writing. If you put the "backup" buyers on the back burner, while you already have a buyer dragging their feet, you could irritate and lose all of the backup buyers if the first one backs out. I've seen it happen more than once.
Here's the best strategy, in my humble opinion:
1- review all offers with your agent
2- determine #1 and #2 best terms/price/condition offers.
3- If offers are too close together, your agent should be calling all agents who submitted offers and ask for highest and best by X time and X date (within 48 hours). In the meantime, see who responds with the most timely, serious offer, and who is highest/lowest risk. Be aggressive and remember to stick to a rapid rate so buyers dont 'cool off'.
4- Implement the 'first right of refusal' if a buyer falls through and move quickly if this should happen. The longer you wait, the more of a risk you run of losing an excellent buyer.
5- proceed aggressively and keep the faith!
*If another buyer comes in with a better offer than the first people that are getting inspections done, then let the first buyer know that there's more offers coming in, and to be fair to all parties, you must give each a chance. If you choose another buyer, you will most likely have to reimburse for the cost of the home inspection.
Overall, it's a risk no matter which way you go. You risk the first buyer and while he/she is wasting time, you are risking losing the backups as well, so play your cards strategically.
Hope this helps and remember to keep in close contact with your agent. A day lost could be $10,000 lost! :) Best of luck and let us all know of the outcome!