Strange, i've run tinys at 1.8V with no issues.
But i agree with above, as much as i love AVR's there isn't much point getting into them when ARM is so close to replacing the low end MCU market.
If you want something easy to learn look at the Arduino, if you want something to teach you a good platform which will be around for ages, choose ARM.
In reality it doesn't matter so much as programming skills transfer between platforms pretty easy.
So if you really want to learn PIC, go for it.
Don't get forced to pick a different platform just because others say so.
The most important factor is that you enjoy it and your more likely to give up when things get hard if you're using a platform someone else recommended and not the one you really wanted.
Also, don't learn ASM unless you actually want to or are interested in it.
Its nice to understand ASM and how things work at that level but its not required.
Use C, it makes things much easier.