You can take a 1 to 3 day trip to the Mekong Delta, I highly recommend that. The backpacker area around Pham Ngu Lao has lots of guesthouses. In particular, there's a small alley only big enough for people and motorbikes that has guesthouse after guesthouse. The motorbike drivers are pretty tricky, so be wary of them. The traffic is scary, cross when the locals do. Also check out the war crimes museum, it's very enlightening.