For managing a large number of waypoints - that is to create "maps" - Trackmaker (gpstm.com) is most useful. csv formats are similar, but some edit required to get it to work. Especially the proximity field and waypoint-symbol conversion is hard to get right without painstaking manual tweaking.
As data exchange with one of the gpstm.com formats to edit large collections of waypoints might just result in community development of waypoint sets for different places.
Display of vlkGPS waypoints in gpstm encl