Re: favorite/best practice amp?
if you are bringing a capable laptop with you on business trips, i'd say the best solution is to get a line 6 toneport interface and grab a cheap set of portable computer speakers. you won't exactly be treated with the best tones in the world, but the cool thing is that just about every interface these days comes with light recording software and a myriad of guitar sounds built in, especially the line 6 stuff.
my laptop, portable speakers, and interface are all i pack if i want to practice on the road. overall, you'd be looking to spend around $170 for a setup like this; $130 for the interface and either a set of over-ear headphones or speakers depending on which audio situation you'd rather have.
edit:
btw, as far as a good classic metal tone goes, the line 6 gearbox has a bunch of '80s metal' and other heavy presets built in, along with a bunch of classic high gain amp head, cabinet, and pedal models. personally, all i ever end up dicking around with these days in my gearbox is the jcm800 setting with the 'green screamer' pedal along with some reverb/delay on to get the classic 80s metal thing happening.