Blizzard pretty much has the level 70 PvP rewards set up already. In the current state, there will be a 5 piece level 70 blue set and a 3 piece epic set for each class purchased with normal honor/marks. There will also be a slew of blue quality weapons, some blue/epic trinkets/gems/necks, etc... that can be purchased with honor/marks. The epic quality weapons, and the 5 piece arena set for every class, are all purchased using arena tokens (the equivalent of "honor" but awarded through the ranked arena system).
What I would personally recomend:
- If you play a melee class or a hunter... definitely without a doubt grind for your primary weapons. This will make the 60+ grind go faster at the beginning. There's a huge difference in swinging dal'rend's main hand and a GM/HWL 1h sword.
- Upgrade pieces of your kit that are from the level 60 blue instances. If you're already a casual raider, and you have gear from MC/ZG, it might not be worth it to make the honor grind (might be just better to save for level 70 stuff). However, if you're rocking tier 0 gear, the r12/13 gear is likely a BIG upgrade and will help you grind faster in BC.
- Get pimp looking gear. Hell, I know people that are doing the grind just to get stuff like the HWL staff b/c it looks so cool. After I make my grind for weapons, I'm debating picking up the whole HWL set. Granted, it will be soon outdate. However, honor is not that hard to farm, and it's fun for me. I already have superior gear for raiding (I really don't need 6k unbuffed health as a rogue... and it gimps my DPS output). However, I just love the way the PvP set looks...
With these things in mind, realize that you can only save honor tokens to a certain point. At this time, it's capped at 2x the cost of the highest priced items which are the HWL/GM 2h weapons at about 44k honor IIRC. It definitely might not be a bad idea to atleast have some saved for when BC hits (I know I'll be saving a good chunk). However, you'll also have the fun of PvP at level 70, and will gain some honor along the way.