Never been asked myself yet, can't see there any problems though, as long as you give it some thought before you go lashing them down!
Random tiling? Let the custom set them out in a spare room or the lawn, if you do it and they don't like it!!!!! Below is a link to a program which does random pattens, type in No of tiles and No of colours etc. Used it once and customer was impressed. Only thing was, it wouldn't run on my computor because of high security on my pc but it ran OK on customers pc.
http://www.iansharpe.com/art_xltiling.php