I'm probably the only person on Earth who will recommend The Pacific over Band of Brothers. It's probably one of the better depictions of the PTO in a Hollywood production, and the combat sequences are pretty much the most terrifying put on screen. Jeeps wasn't kidding when he said they're incredibly graphic. Also, for me at least, it avoids my biggest issue with Band of Brothers which is that implication that E Company 2nd Battalion 506th PIR was somehow the best US Army Infantry Unit. A lot of The Pacific shows that 2/1 and 3/5 Marines were just cogs in a much larger war machine.
With that said, I also want to echo what Tied said. Generation Kill is pretty fantastic. It focuses more on the day to day interaction between Marines while overseas than combat. In fact one of the major focus points is how much 'Hurry up and wait' is involved vs actual combat. IMO it's probably my favorite HBO War series.