Does the "west evens / east odds" rule apply when flying without a specific destination (sightseeing, etc)?
14 CFR 91.159 says:


  Except while holding in a holding pattern of 2 minutes or less, or
  while turning, each person operating an aircraft under VFR in level
  cruising flight more than 3,000 feet above the surface shall maintain
  the appropriate altitude or flight level prescribed below, unless
  otherwise authorized by ATC: [etc.]


So if you're above 3000' AGL and not turning or in a hold, then you're required to follow the odd/even rule. Personally, I've never found it to be an issue because if I'm on a sightseeing flight or just following a river or whatever for fun then I'm usually below 3000' AGL anyway (and 91.159 is one of the reasons why).