Are there lengths of feed line to avoid or ones that may cause problems with an antenna system? For single band use. Appendix: The run of coaxial will be for the 10 metre band. I would imagine this has no or little relevance as lengths can be expressed in a manner for any desired frequency.
Unless your antenna system relies on common-mode radiation of the feedline (most do not when properly installed), feedline length is irrelevant to the operation of the antenna. So, the usual approach is to make the feedline as short as possible (possibly with a short loop somewhere, for future maintenance) since a shorter length minimizes losses and cost.