As a follow up logistically if you do plan on riding all the SkyTrains, for Expo/Millennium I would suggest:
1) Catch an Expo to King George train from downtown to King George.
2) Main stops along that stretch would be Joyce-Collingwood, Metrotown, Edmonds, New Westminster, Surrey Central, and King George (end of hte line)
3) Once you do that stretch catch a train back towards Downtown then hop off at Columbia in New West (first stop heading to Vancouver once you cross the bridge over the Fraser)
4) Switch to the other platform and catch a Millennium Line to VCC/Clark.
5) Key stops along that stretch would be Sapperton (Brewery), Lougheed, Brentwood, then Broadway. Probably no need to go all the way to VCC/Clark, just get off at Broadway and switch back to the other line heading into downtown / or jump the 99 at Broadway out to UBC.
Canada Line can be done on its own as it is disjointed from the other two lines.
http://tripplanning.translink.ca/FIL...yTrain_Sys.pdf
Also for reference, a SkyTrain ride from Waterfront to King George (furthest point) is approximately 40 minutes and Columbia >> Broadway via Millennium is about 25 minutes so not a large amount of time and riding all the lines can be done in a day easy.