Block BB: what you've said... depending on stage height you need to look up all the time. You wont have an overall view of the spectacle. "Frog" view. You're probably looking almost directly in the lighting all the time. And it is way to much to the side.
Note: such front row seats are usually never good!!! No matter what the show it is or where it is taken place. Unless you're coming to the show for that one actor or whatever and want to kiss his/her feet
Although many people say they see everything very good from the first rows, it is actually seldom the case. Shows like that (and theater shows in general for that matter) are never made to be viewed from the first rows! You will always miss a big part of the grand picture.
Best row is between 10th and 15th row in the first block in front of the stage, in an average theater and in arena's, no matter what show. In a theater, those rows are also usually the rows right in front of the sound mixing boot (in case it is located between the seats, and not in the director's boot far behind the balcony). They also have the best sound (hence the sound boot is quite often located there in live shows). For arena's, the sound mixer is usually way more in the back though.
If block J wasn't on row P, then I would have choosen that one. But row P is way too far...
So, that leaves block K... although it is also a bit to the side unfortunatly. But for this show, that doesn't matter too much though. (in some other (theater) shows you might see stuff you shouldn't see though).
Note: presales and other sales are often done to fill up the gaps. This could mean that those seats aren't as popular as others or might have a restricted view (otherwise they don't need to fill them up). I'm not saying this is the case for this show, but it could be...
If there is a website to order your tickets, I would first check that out. Quite often you can choose your exact seat on such sites. If that is the case then try a few times until you find the best seat for your likings. Also remember that the option "Best seat available" will _not_ always give you the best seat available!! You're better of selecting the categories yourself.
And, there are usually more than one ticket sites/boxoffices available which offer tickets. And each have very often their own sections/rows available for sale. So, if you can't find a 'good' seat on one site/boxoffice, then check the other:
http://www.ticketmaster.co.uk/search?tm_link=tm_h...altimbanco+Glasgow
http://www.ticketsoup.com/TSEvent.aspx?EventID=11...%20-%20Saltimbanco
At first sight ticketsoup has far better choice than ticketmaster, including block CC and DD, and a bit cheaper!!
Also check if there isn't a detailed seating plan available where every seat can be seen individually. This plan can often be found on the site of the theater/arena/hall itself in the "technical rider" or "download" section under "rigging", "seating", "technical drawing" or similar items. (only rarely found on the site of the show or on the ticket service site).
Photo's of the concert hall where CDS will perform in Glasgow:
http://www.secc.co.uk/organise/concerts-and-event...-halls/hall-4.aspx
You can use those as a guide for the seating plan if you can't find a more detailed map than the one you have. But note that seating plans are often a bit different depending on the kind of show or event, etc.
EDIT:
here is a detailed seating plan. But I dunno if it would be very usefull because the seatings on the floor are placed and numbered differently for the CDS show (the balcony/tiered seatings are numbered the same as your small plan though). So be carefull.
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Have great fun! I don't quite often say that, but the premium price is worth it for this show (for most shows from CDS actually), if you have a proper premium seat of course...