On my iPhone I use the Official Google Voice app along with GV Connect: http://goo.gl/6Mh9E to use both Google Voice numbers at the same time. I am looking for something similar to GV Connect for Android.
Currently I use the following 4 methods to 1. View SMS 2. Send SMS 3. Make Phone Calls. 4. Recieve SMS notification on an Android Phone.
1. To View SMS: I created a widget of the Google Voice website that I use to view messages in the Chrome Beta. (Also forward SMS to my Gmail and have a custom notification for the SMS Label I created in Gmail.)
2. To send SMS: I use Group SMS & Scheduler http://goo.gl/Vtwpo.
3. To Make Calls: I use GooveIP http://goo.gl/iTczt
4. SMS Notifications on Phone: I set forwarding of SMS messages on my secondary Google Vocie number to my gmail. Then created a Gmail label for all SMS messages to a particular label and skip my inbox. I then setup a custom notification sound for this folder so that I can get notifications on my phone.
There has to be a better way than this. I find it hard to believe that an iPhone is head and shoulders above Android when it comes to using Multiple Google Voice numbers.