Originally Posted by
onaswan
As you point (oops there I go again) out Gold / Silver are worthwhile when you travel a great deal -
when you are going to get the TPs anyway! 
I wouldn't!
Predominately my travel is for leisure - but in a commuter sense.
In the past this involved lots of EuroTraveller on as cheap a fare as possible - an offering I'm very happy with. (Sadly since the demise of GT it has been vary hard to keep much on BA as I'm under served with flights where I am.)
Generally I pick up the odd set of tier points here and there from work travel, but they would be wasted if I didn't add to them (I.e. I'd be very far away from Silver)
So why do I sometimes spend money that I don't need to spend (either extra trips, or higher cabins) and am now a silver?
1. It's nice to be pampered a bit once in a while.
2. Lounge access adds considerably to my travel experience, so, given the levels of BA flights I used to take it made sense to go for it and have the card.
3. BA Miles, my ET flying got me enough miles to not be dismissed, but equally I didn't earn them fast enough for them to not be undermined by the ongoing (effective) devaluation.
- My extra trips, and CE upgrades on normal ones are not only fun, but they also bump my miles to useable levels.
If I just flew on the minimum spend I needed to, I'd be happy enough with the onboard product (minus the occasional pampering), but BAEC would have nothing for me.