Just to add, you want to also try to keep each site on its own site tag unless you have small sites in which you might have a site tag per region. Never try to max out the number of access points also if you can avoid that. Like what @Arshad Safrulla mentioned, stay below 500 if possible. Look ahead at what you might be changing in the future and decide if the change would affect all ap's in the site tag and if that is okay with you.
-Scott
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