All good recommendations I can add a couple that might be helpful.

Plan on shooting the subject at least twice. Bracket the heck out of the first shooting. You may wish to even use a couple different films the first time to be sure you're on the right course (a daylight and T film would be my suggestion).

Proof the work prior to reshooting by actually making enlargements. A tough 11x14 enlargement won't get easier as you get larger and yet a neg that is touch thin and easy to enlarge at 11x14 may very well fall apart when printed to mural size. So do a mag test. Print the neg as large as you can onto as big a sheet of paper as you can process.

If your happy with the results--cool. If not, make your adjustments, reshoot and do the enlargements and mag test again.

If shooting MF and at night (long exposures) I would recommend Reala, NC (or VC), 100t (or NPL) and possibly Ultra 100 (I haven't used the ultra much at night so can't be sure) in no particular order. Well I would lean toward NC, 100t and Reala in that order. I would also strongly advise balancing the light as best you can with on camera filtration -- you don't want to make your life or the person doing the enlargement's life any more difficult than you need to.

I would not recommend Velvia, at least in my experience it suffers badly on long exposures. In my experience with chromes, those that perform better on longer exposures tend to have courser grain. On the flip side I love grain and would not think twice about shooting this with EPT (ektachrome 160T). With chromes the problem then becomes output. Printing from a tranie to traditional materials is not as easy nor are there as many choices as there are from a neg.

Although I didn't shoot it, I did the prep for a 9'x12' mural enlarged from a 35mm kodachrome 25 tranie. There was some digital steps involved, but the dye clouds/grain of the film were like nothing else and the final product (an RA dura trans) was not just excellent for a 35mm, but excellent from any perspective. Of course that doesn't help you.

The final comment I would make might not be too well received. If this is a commercial product and it needs to be 'clean' if not slick from normal viewing distance to close up then consider ADA. (Shoot large film, drum scan, D output to appropriate RA or Ciba material -- or would that be ADD) [/SIZE]