any possibility you can play both by using 2 clients? You can quest both of them up, being able to kill on scout and have heals from priest. Then in the long run, you'll have 2 toons being leveled, perhaps your gf would want to play. then you can play the p/r and she can play the s/wd or vice versa.
im not sure if you are in a guild or not, but a guild with lower levels in mind would be really helpful in your leveling process, whether it be from helping you quest, or porting to certain zones, or just having buffs (high level buff towers are super good for leveling).
it'll be super nice if you could double box, so you can have both toons leveling, while you still decide what you want to play