I have only just joined this forum and was having a browse around and spotted this post and had to reply. I have been a customer of Blue Realm for nearly 4 years now with trips out to Dahab about twice a year. When I first dived with them I booked on the basis of the informative website and the response I got back to my enquires but the experience once in Dahab exceeds this and I have kept diving with them ever since.
As String says above they are a smaller dive centre, max 18 guests, but this makes for a more personal service. There is a strong emphasis on safety and I have never once felt that I was not in capable hands. When taking out guided groups they will not exceed more than 4 guests to each guide and they always try to match people with the right experience levels. If different groups do not go together well they will often use another dive guide to ensure that everyone stays happy, even if that means they end up with a ratio of 2:1 in several groups. I can not say the same for a number of other dive centres in Dahab, on many occasions I have seen groups of 8, even more, with one guide!
You do not mention what kind of diving you plan to do but if any in your family plan to do a course then this experience will also be first rate. I did my Rescue course with them and friends joining me have done Advanced and Open Water also and we all had a ratio of 1:1 on the course. They will start courses to suit your own preferred date, rather than being told we have a course starting on X and you are expected to then fit in with the schedule. When observing other courses underway I have never seen a higher ratio than 1 instructor to 3 students (usually all from the same family/ group) and many times 1:1 as we had. This means you can progress at your own speed and it is effectively a 'private' course, something which many dive centres would charge a premium for.
I have also stayed at Blue Beach hotel for many of my stays and would recommend it also. The staff are friendly, its popular with all types of groups (inc families) and nationalities which makes a really nice atmosphere, breakfast in the restaurant is good (and as String says so are the steaks and the burgers!) and all rooms have either been recently renovated or are in the new building which opened less than 2 years ago. The dive centre is on site, so you literally roll out of bed, walk a few metres to breakfast and then walk a few more to go and kit up for diving...it doesn't get much easier.
You may well have booked by now as I have picked up on this thread a little late but if you haven't then I would suggest booking your accommodation and diving through the dive centre as you can get some nice packages inc transfer from Sharm airport that work out cheaper than booking both separately.
