July cruise questions



My daughter is getting married in July 2004. She is interested in doing either a trans atlantic re-positioning cruise or an Alaskan cruise. If anyone can help me with the following questions I would greatly appreciate it.

1. Where can I find some information on any re-positioning cruises that may be taking place next July such as cruise line, ships, availability, costs, and ports?

2. If she chooses Alaska, who does everyone prefer, RCCL or Celebrity?

Which ships from these lines?

I heard that there are 2 different intineraries for this cruise. Which one is better and why?

What is the weather like during July in Alaska?

Is a 7 day cruise long enough or should she look at extended cruises?

Thank you in advance to everyone who replies to this message. We really appreciate your help!