I've used Whitewall and they do very nice work. I wish though that they used ROES or something equivalent so that there was some ability for instructions to be passed to them. For example, there seems to be no way to ask for them to print at a specific DPI. Their Lightjet can print at 200 or 300 DPI. If I'm taking a 5D3 image to, say, 24" wide I'd like it printed at 300 DPI, but if I'm printing at 36" or wider I'd want it at 200 DPI (as that's what I'm sizing it to in PS for output sharpening). As far as I can tell they print everything at 300 DPI; multiple emails to support got no response and they do not answer the phone. I'm also not at all crazy about having to convert to sRGB when submitting images.
You should take a look at West Coast Imaging. They will accept aRBG images, you can call them and actually talk to someone on the phone and they are consummate pros. And they do phenomenal work (and package accordingly; Whitewall is known for not packaging well).
If you want those images to pop have them printed on the Lightjet Fujiflex. It's more expensive but totally worth it. You might consider having them print a 18"x12" as a proof just to see if your monitor shows what the print shows before going for a larger size. I know you want it framed, but also consider doing a a Fujiflex under Acrylic (looks amazing) or try a print on metal (not metal paper).
Before submitting to any printer, make sure if they require that the image has no alpha channel masks, 8/16 bit, flattened, what color space, etc.