Rihanna vs. Lea Michele Hot Bikini Bodies [PHOTOS]: Booty-Flaunting Vacation Snapshots Go Viral, Which Beauty Rocked Sexier End Of Summer Look? [POLL]

Summer's officially coming to an end - but Rihanna and Lea Michele aren't ready to say goodbye to those warm, sun-kissed days just yet.

The "Glee" beauty recently celebrated her 28th birthday with a relaxing trip to Mexico:

msleamichele: "Thank you so much @garzablancapreserveresort for an amazing trip! Best birthday ever! #Mexico."

msleamichele: "Tropical paradise! @garzablancapvr #Mexico."

msleamichele: "A very Happy Birthday."

Meanwhile, RiRi soaked up some rays with girlfriends aboard a luxury yacht in St. Tropez. The "Diamonds" songstress may not have an official Instagram, but that didn't stop these stunning bikini pics from going viral...

Gorgeous. So, which starlet rocked the hotter end-of-summer look?