Domenic,
I am by no means an expert on the topic but I did make the trip to the Skeena drainage two months ago and picked up some knowledge.
First off, I would go prepared to shift tactics as conditions change. We planned for 10 months to fish the Kispiox only to get there and find it blown out. An hour and a half drive to the Bulkley yielded fishable water for two days. After that, every river in the region was blown out for the rest of the trip. Don't be surprised to find one or all the rivers blown as this is not unheard of.
You mentioned staying in Terrace. I would think about staying closer to Smithers as this is closer to the center of the areas rivers.
Depending on what rivers you fish, your choice of flies and gear will change. The Bulkley tends to be a floating line river with smaller dries and damp flies the norm. The Kispiox is a sinktip and big fly river. The Babine, Suskwa, Sustut and Skeena all have their own personalities.
We chose to do it ourselves and not go with a guide so I can't offer any advice in that regard. If you are planning to fish the Kispiox, the Kispiox Sportsman's Lodge was a great place with helpful staff. Remember though that if you book there and Kispiox blows, you have a 3 hour round trip drive to the Bulkley.
Other than these hints, the only thing I can tell you to expect is nice people and incredible scenery. Be careful though, it can be addicting.
Sinktip