Just traded in my last generation Paperwhite for the added credit in order to upgrade to the higher resolution screen. Only question is, is the Voyage worth the cost premium? I might go Special Offer-less this time actually regardless. I haven't bought anything through the Special Offers in probably like two years.
The newest Paperwhite and the Voyage are close. I have the Voyage and really like the flush glass covered front (They gave the glass a micro-texture so it feels very nice), the resolution is slightly higher and the device is lightweight but so is the Paperwhite. If you read a TON it is worth the premium IMO but if you only use it occasionally I'd just go with the newest Paperwhite. You can always disable Special offers later on if you want.