Saeco Aroma ... steaming about 12 oz. of cold 1% milk in a ceramic container that's about 2.5x as tall as it is wide. Using a thermometer.
Opening the steam valve anywhere from 1/3 to all the way.
I can make good foam with the pannarella, but even without deep-submerging the wand I find that the milk reaches critical temperature with only about 15% of it converted to foam. The thermometer is in nice and deep, and the milk is indeed hot. But every drink is a latte - there's just enough foam to put a nice top on it.
Have you read any of the "milk frothing guides" floating around here and there?
I'm not sure from your post, but you are using the pannarello wand? Using the wand should produce lots of big bubbles that will sit on the top of the milk and dissipate quickly when you finish.
Try taking off the outer sleeve of the wand, leaving a narrower tube with a single hole in the end.
Before steaming, purge any water from the wand. Let it get up to temperature, but try steaming just before the element turns off (i.e., just before it reaches full temperature). This will help keep the heat going as you steam, hopefully avoiding any loss of pressure. The Saeco's have a decent size boiler so this shouldn't be too much of a problem.
However, part of your problem is that you are steaming 12oz of milk! That is a lot. The Saeco boiler might be able to handle it (my Gaggia would start having trouble), but it will be difficult to move around that much milk effectively. Any drink would be a latt
Ahem - the 12 oz. of milk was for TWO drinks. I'm not a $%$ Starbucker <grin> I can make them one at a time, I suppose.
I tried some tests without the pannarella, but I forget why they didn't go well. I will start over on that leg of the trousers of history (as Terry Pratchett puts it). Certainly with it in place the parabola effect just isn't a go at all.