I don't play PvP or WvW...
So organised intanced PvE or open world PvE?
If instanced (ie dungeons) then you're better off rerolling to a different class.
From my very limited pve experience, there is not much variety - basically you spec full glass cannon and rotate your phantasm cooldowns to maximise your damage.
Also you trait mantras for the increased damage bonus.
I think since the big patch it is possible to run Sinister gear (condition damage, precision, power) for hybrid builds in pve, but I don't know.
People will give you a hard time if you use things like Greatsword or Staff in dungeons, especially in organised groups - you want mainhand sword in order to cleave (hit multiple targets) as well as having the most damage in melee range.
In open world however you can run whatever you like - it's so brainlessly easy to play that everything works.
Try staff + greatsword with traveler runes (movement speed) or x/focus (x= scepter or sword).
The best gear on mesmers is berserker/assassins (power), sinister (hybrid), rabid/dire (condition). Then traveller runes are what you want for movement speed if not using offhand focus or signet of inspiration for the swiftness. You can also use things like Hoelbrak (power), Nightmare, Perplexity, Undead, among other things.
Once Chronomancer is available it will have a built in 25% movement speed so you can have more freedom in rune choice.