Yep, seamless cotton undies are the dog's danglies
(no pokey underwires are a must too... only relevant to some, obviously... in saying that though, I remember a deft trick by Tiffany Coates that made great use of the underwire... okay, maybe only comfy ones then)

Besides the sheepskin - which I used for sizable trip, but ended up putting out to pasture because I just started to get grossed out by it LOL - get hold of a gel pad. The ones used under horse saddles to prevent discomfort/chaffing are perfect. Nothing like a lovely cushioning for your tushy!

You could always include regular seat shuffling and clenching to get the blood flow going, if all else fails!

And on the 'tired' side of things:
Fluid intake is crucial! If you keep yourself hydrated, you are less likely to be fatigued because of dehydration (which is an automatic 10% loss of 'oomph'!... apparantly). Invest in a camel bak.

And SING

Sing to yourself, take photo breaks (which will get your poor hiney out of the seat for a while) and keep your brain awake. If you spend 30 minutes looking for anything purple whilst riding (for example), you're more likely to be more alert than if you were just day dreaming about the beach you were to reach in 3 hours time (which you wouldn't be able to do anything on because of having to wait half an hour for your left butt cheek to revive... unless you're the 'make an entrance' type, and don't mind throwing yourself off your bike in order to get off )

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