Great to hear that the light control is to be so excellent. I personally think 135" is too small in that room. There are even a lot of flat panel owners who have a more immersive viewing angle than say 25 degrees, however, you never stated what your seated distances might be. Are you thinking one row at 16ft, another say about 23 ft?
If you do two rows, make sure that the back row is not too close to the back wall where muddy bass will collect. In a room that long, there is no excuse not to give the back row at least several feet from the back wall.
I sit closer than 16' and I still went with 159".
Fire the pic at the blank wall first. This is always my best advice, IMO.
I'm not sure where Sherardp picked up that a 135" is to be well over $700. Mine was just a tad more, even with the unnecessary additions of CSR and custom ordered in black. HP is so affordable. However, if you use it, you really have to do your best in getting the PJ closer to viewers' heads. If you ceiling mount, please consider a longer pipe to be able to do so. A cool tip I picked up is using less extension of pipe when bulb is new, and extending the pipe as the bulb ages to create a more direct angle, and thereby increasing the retro-reflective gain to the viewers' eyes.
Its all been discussed, please use the search function for basic questions for starters. Cheers.