Wirelessly posted (Mozilla/5.0 (iPhone; U; CPU iPhone OS 4_3 like Mac OS X; en-us) AppleWebKit/533.17.9 (KHTML, like Gecko) Version/5.0.2 Mobile/8F190 Safari/6533.18.5)
Ummm. The wi-fi iPad2 is the device you are wanting to provide the hotspot to, right?
If so, then tethering your iPhone is good if you know your coverage map well...and stay within the bounds.
I believe that method or a personal hotspot is the way to go because you can connect other devices to either.
Also, hotspots will upgrade to 4G and so will phones. The iPad is a static device. Software upgrades yes, hardware upgrades no.
You will have to read other threads for the personal hotspot meant for you, if you go that route.
Peace,
gdc