I have an F5.9 8" dob and I LOVE the Explore Scientific 82 degree eyepieces. I have the 8.8 and the 6.7. Will add the 11 at a future date. I have a 2" 2X barlow, 1.25" 2X and 3X barlows to extend my eyepiece collection.
Zoom - If you want to get a wide range of magnifications for a relatively modest investment, the Celestron 8-24 zoom is my most used eyepiece. Gives me 50-150 by itself. Drop it in the 2X barlow and I have 100 to 300. Not as wide as the ES 82s but I have everything with the zoom and the barlow. Over time I have added in single FL eyepieces as I have felt the need but this is still my most used eyepiece.
If you like the idea of the zoom and have a larger budget then go for the Baader Hyperion 8-24. 25% wider FOV than the Celestron and likely better overall optics but 4+X the price.
http://agenaastro.com/eyepieces/zoom-eyepieces.html
zoom eyepiece review
http://www.chuckhawks.com/comparison_zoom_eyepieces.htm
But even at the price of the Baader it is around the same price as 2 ES 82s and far more versatile. Some people say the Baader is now their only eyepiece.
BaaderHyperian III Clickstop zoom review
http://www.weasner.com/co/Reviews/20...ece/index.html
If you want to go single FL eyepieces then I would suggest the ES 82 8.8 mm first. A more practical jump from the 15 mm. That would give you 136X which can be useful on moon, planets and on DSOs. Slip it into the 2X barlow and you have 272X. A more versatile combination in my opinion than the 6.7 if you can only get one right now. If you can get both then the 8.8 and the 6.7 are a great combination.
I don't know what your sky conditions are like. I live just outside New York City so my light pollution is bad. I find that, between LP and seeing, I rarely get over 250X except on the moon. Most of my observing is done closer to 200X.
I use the 6.7 by itself a LOT at 179X but I also have a Meade HD60 4.5 to take me to 266X, that next level of magnification and typically, again, I only use this on the moon as the seeing often won't support this for other targets.
I have used my ES 82s in 2X and 3X barlows in my 80/400 refractor and they work just fine. You still get that wide view effect.
If you don't want to use the barlow then the 6.7 would be the way to go but don't expect to do a lot at 360X. But your smileage may vary a lot from mine.
Clear skies!