The problem is it can take a long time to find someone interested in the brandability, as no-one is likely to be thinking of a sunnier brand right now.
You have to decide whether you want to sell to an end user (lots of work, finding, promoting, etc etc) or to a fellow domainer developer (quicker, easier, but lower sale value).
Ultimately any marketing you do is going to help but probably won't generate immediate pay-off.
Otherwise, promote it as much as you can to fellow developer/domainers, e.g. here and affiliates4u.com etc etc. If you use Sedo, you can set a min offer price, then once you've accepted that min offer you can use it as a reserve in an auction - you've sold the domain at min offer, but you can then try and realise further value through auction.
Rgds