Correct placement of devices on a Fibre Channel fabric

sorry for the delay.

Had a look at what you've got and what you want to achieve, I had a few thoughts, here's a nice picture first...

• There seems no point using an 8Gbps link between sites just now - the reason is that you're constrained by the 4Gbps ports on the remote 4400, you’ve got a stable 4Gbps already plus the available bandwidth is much higher than the actual usage requirement - it just seems a waste, today, to put one of the 24x8 switches over there. I'd use two of the 16x4Gb switches at the remote site.
• I'd be tempted to use the new 24x8 switches as your main 'core' switches - most of your traffic is server-to-6100 and the new box will be much faster. This way you should see some, small, performance gains as the new switch has larger buffers and lower latency, plus you can pick and choose which servers to move to 8Gb as and when you like, same for when you swap out the 6100 (the 4600's have native 8Gb ports but that's not official yet ;) ).
• We then get into a part of the design where we have two options; to keep or discard the two 16x4Gb 'middle switches' - purely based on port count. Basically if you used the 24x8 switches as core boxes you only have 3 spare ports (as you'll use 18 for the 18 servers, plus 2 to the 6100 and an ISL link, equalling 21 used). You could connect the local 4400 to the 24x8 switches, leaving you exactly 1 port free for your tape drives but that leaves you with zero free ports. What I'd be tempted to do is use the two 16x4Gb 'middle switches' either as secondary local switches to handle the local 4400 and tape drives or possibly to handle the inter-site ISL links if you wished - although you'll have ports free on the 24x8Gb switches to do that directly from there if you wish - I haven't shown both as they're really very similar.

So that's my thoughts - there are tweaks to be had all over but my general ideas are there - feel free to come back to me with any clarifications.