Don't panic. Yes, it can be tricky to get to the front on the Ch'Ely, but you can still be three back with a good'ish view if you just turn up when the cycling starts. Having been to every tour for probably the last 10 years I can honestly say that standing in the same spot on the Ch, Ely would drive me mad. Vary your veiwpoint. For one of the routes stand on the 1st floor of Virgin records megastore and watch through their window (staff not as fussy last year as they used to be). Then pick a few different spots along the road or upstairs in Quick (a fast food joint). It's Paris - relax!
As for hotels - they aren't a problem. We've never struggled to find anything. I would recommend Le Meridien Montparnasse (4*). We usually pay about £120 a night. Montparnasse is by far our favourite area of Paris. Great shops nearby, easy tube connections etc, resteraunts and it's near a great cemetary. (Do some research for all the famous burials - although it pales into comparisson to the stunning Pere Lechaise cemetary.) Whatever you do, visit the Catacombes! Only 15 minutes walk away.
The best bit about Paris in the summertime is that all the Parisians have headed down south on their holidays which makes it an extra relaxing break. Paris is amazing.