28 May is the day before a major holiday.
La Ciotat is a good alternative base. I really like it. It's a bit gritty with a small shipyard right in town, but only just a bit after years of major improvements and renovations - and seeing the cranes against the cliffs in the background is quite dramatic IMO. There are lots of cute shops and restaurants in town (don't sit at any random restaurant on the harbor though. Check reviews first, some are very bad), and pretty coves at le Mugel and Figuerolles. You'll find few foreign tourists.
The Best Western by the harbor is really a prime location, and it has good rates for the 28th. French Best Westerns are much better, fancier hotels than their US counterparts.