As long as we are passing out warnings concerning the festival, here is another. Although it might seem like just part of the fun and revelry, try and avoid as much as possible getting spattered with confetti. They sell little bags of it that you can throw around yourself too, but don't contribute to that market. If you look carefully most ticos, primarily K*ds, are too cheap to be bothered paying for the little bags. Instead they scrap up the used confetti off the street and recycle it. That might seem harmless enough until you consider that patch of street may have been where a drunk had taken a leak the night before or where some TB-ridden tico had spit during the day. It may seem like just another alarmist thing to worry about but the Tico authorities have labeled it a serious health hazard and every year try to warn and discourage the public about this one aspect of the Festival, usually with little impact.
Some other advice. If you want to be able to actually see the floats halfway decently, you'll either have to be invited to a private party in one of the buildings overlooking the parade route (or throw your own
http://www.costaricaticas.com/phpBB2/viewtopic.php?p=58456&highlight=luz#58456) or if at street level stake out your spot very early. If you're assertive you can muscle your way through the crowd later to get fairly close to the street but you'll still probably be standing on your tip-toes to see over the heads of the crowd. Another thing you can do is to rent a stool to stand on which some vendors will be offering. That might help a little but keep in mind, many others will be doing the same thing or at least bringing theirs from home and so you might just wind up at the same level as everyone else anyway.
The ticos are very proud of their Fiesta de la Luz parade, but I can tell you Macy's in NY or the Rosebowl people in Pasadena have nothing to worry about. YMMV
http://www.costaricaticas.com/phpBB2/viewtopic.php?t=6761&start=2