I kinda like strange rules in contests, like the Stew Perry 160 using grid squares and distance scoring, or the long exchange in Sweepstakes.
I also like serial number exchange contests - actually having to copy something other than callsign and thwarting the Call History files.
Throw in the sometimes bizarre prefixes that show up and WPX is usually fun - I do usually make sure to do a late am sweep or 40 and 80 and work the VEs CQing there!
I have a club call (KK3TN) I forgot to trot out for WPX. K3 is not rare, KK3 is - can really tell the difference after I get spottted!
But, for a US op, Memorial Day weekend (unless bad wx cooperates...) is usually a tough weekend to put in a lot of time.
73 John K3TN
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It's kind of funny in the wpx contest that US stations get 4 points for working Ontario on 40m, but only 3 points for a really tough contact into China on 15m 
Tor N4OGW