Ok, I probably don't use the lounges as much as some on here, but here is my opinion...
The Lounge Pavillion has the Moulton Brown Spa - which offers CW passengers free treatments and showers. If either appeal, first thing to do is to go to the Spa and make appointments for treatments and/or have a shower. I would then wait in the terraces, upstairs, for any appointment (don't see the point into going to the Terraces at Gate 1, then coming back again).
After any showers/treatments (or if you didn't want any), I would go to the Terraces at Gate 1: it seems a lot more spacious and quieter (especially if you go upstairs...). In my experience, the Terraces in the Lounge Pavillion is very busy, noisy, can be difficult to find seats and quite a few businessmen who seem to letch a bit... (but you may or may not have that problem...

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I was quite surprised the first time I went to the Gate 1 Terraces - thought it would be a little pokey lounge, it is actually quite a well kept secret! So don't tell anyone!
Of course, lounge choice may depend on what gate you are likely to depart from.
Boo