Speaker Cable Lengths - W/ Monos

I'm considering having the manufacturer of my 10 foot cables cut the cables in half and re-terminate them for use with my Monoblocks in a Bi-wire configuration. They are very expensive cables, however, and I'd hate to cut myself short on cable (while also ruining their resale). At the same time, I'd hate to double up the longer length due to costs if I can help it.

My short term listening room will work easily with 4 1/2 to 5 foot cables, however, I'm not sure about a future room I'm planning.

What are typical cable lengths for those of you running monos out there? Is five feet usually enough? How far away from my speakers should my 150 lb. monos be?

Thanks in advance for any assistance.
I have read you should use longer interconnects and shorter speaker cables. For my momoblocks I use 5' or 6' cables. I think it depends on your personal room set-up and/or how happy are you with your current cables. When if ever do you see yourself upgrading them?
Go as short as possible. The shorter the distance on speaker cable the better the sound, and you can get higher quality cable for less $. I have frequently seen used cable in the 4 to 5 foot lengths here on Audiogon. It typically sells at the same ratio (new/used) as longer (i.e. standard) 8 foot runs--so I wouldn't concern yourself about the resale issue to much.
The only thing you should think about is whether you always plan on having mono's in your system. I own a 4' biwire run of AQ Sterling and Clear. I'm VERY happy with the cables but am in the market for a new amp/monos. With the cost of the original cables factored in I'm kicking myself for not getting 8' runs for the added flexibility. Good luck with the decision. By the way, what cables do you have?
I went from 7' speaker cables to 18" ones, using monoblocks. Nothing else changed, the cables were both Stealth Ultimate Ribbon. The improvement with 18" was huge! The subjective impression is of having the music MUCH CLOSER. If you can manage it, with monoblocks, I'd make the cables MUCH shorter than 4' or 5'. It might be better, more cost-effective, to sell your present cables and replace them by new short ones.
I have used both 18 inch and 8 foot speaker cables in the past with my monos, but with cables by different manufacturers so I couldn't give you a meaningful sonic comparison. For what it's worth, I replaced the shorter runs with the longer, and the longer ones (Dunlavy) sounded better than the shorter ones (Siltech FT-12), in my system (at the time, Jadis JA80s into Duntech Princesses). I still agree with the thinking that shorter should probably be better, although with my current setup I need 8 foot lengths. I will note that it was VERY difficult to sell the short pair. I think once you get to 3 or 4 foot lengths, the resale factor may go away, but you will still probably be limiting your market to owners of monoblocs unless you go with a longer length. And given your uncertainty about your future listening room requirements, you may be better off waiting until those plans firm up before doing something to your cables. Hope this helps a little.