Nat recently bought a Toshiba Excite tablet because it had HDMI and offers expandable memory. After only a week, though, it's become very slow for surfing the web. Leo says that the Excite is an older model and isn't the fastest tablet out there, so it's possible Nat isn't getting the speeds she's used to. Leo says she'd probably be happier with the iPad. Instead of using HDMI out, she could use an AppleTV, and use Airplay to stream video wirelessly. Since Nat has an iPhone, she'd be able to use the same apps as well.
As far as Android tablets go, the Google Nexus 7 or Nexus 10 are good options. That'll run the latest Android 4.2 Jelly Bean OS. There's also the Asus EeePad Transformer. It's really fast and she could get a keyboard with it. A Surface Tablet may be another option if she wants Microsoft Office.