This Q&A in regards to emanations suggests that extending some of them from a creature's space rather than a grid intersection is a good way to handle those effects that emanate from a creature rather than from a point in space. I like the answer there.
Preamble: My low-level wizard character is about to embark on a raid on a beholder's lair, and wants to have most of the party invisible. His plan includes casting invisibility sphere (PH 245) on the party and then have them ahead while he's a short way behind in an antimagic field (PH 200) which will be both refuge and trap for the beast. Due to his inability to see in darkness, the need to not alert the beholder to their presence too early by carrying a working light source, and the silence (PH 279) spell he intends to have the rest of the party under, he wants to have a rope extend from the party, most of whom have 60 foot darkvision (which he doesn't possess) so that they can all gauge their distance from each other, as well as send very basic signals.
I got the idea that making the rope invisible wouldn't hurt, and this question sprang to mind:
When cast on a very large or changeable object (like a rope), how do spells like invisibility sphere and silence operate? The invisibility sphere and silence spells say that they can be cast on objects which then emanate the spell effect from themselves. Both effects are also explicitly mobile with the recipient.
Would the effect persist along the entire rope, permitting humorously large groups of silent, invisible creatures who were all within 10 feet of an uncoiled rope (less than 100 lbs of rope in order to stay within the invisibility spell's limits)?