This is my name, and I love it. My mum is French, but generally I use the German pronunciation of Rainer just to make it easier. But as a francophone, it is a beautiful uncommon name especially in English said the French way.
Although this is a beautiful name, it reminds me of the weather that is more rainy than rainy. However, as it's pronounced differently than said weather, I have mixed feelings.
Rainier Brewing Company made Rainier Beer - Iconic for many of their commercials including the one of a motorcycle that revved "raiiiiiiiii-nieeeeeeeer-beeeeeeeer" while zooming by along a mountain road.