ladykalessa pointed out a thread on the FB Elizabethan Costuming list (EC Bees) that is currently discussing cloak fasteners for gentlemen's clothing. The discussion is varied and well thought out and being attended to by some of the best researchers I know in that period:
If you aren't on the EC Bees list, I cannot recommend it enough. These sorts of tidbits surface on there so often that one can Not Keep Up with the data stream most times...
Some specifically interesting bits for me included the following potential options for keeping capes in place; interior straps (ala fur stoles), hooks (which were generally not seen as a better option than ties, since both have the potential for destroying the fabric of the doublet layer) and PINS (which was my first instinct, and I was happy to see that Ninya Mikhaia also thought likely). I also tend to think that the *cut* of the garment is critical, and suspect that greater-than-half-circle capes stay in place more easily as they fit over the shoulders better and distribute a greater volume of fabric/weight to the front of the wearer.
Additional info regarding cloaks in JA's PoF:
https://www.facebook.com/photo.php?fbid=10151854825249221&set=p.10151854825249221&type=1&theater Images of cloaks in use during dance:
http://www.pbm.com/~lindahl/negri/images/