First of all I wanted to reply you on the same day you posted this note, but this sajha has stupid registration process which caused this delay.
Anyway coming to the point-
I sponsored my dad and he got visa a month ago. Alike you, I am also in H1B, working as full time IT professional.
Documents I sent him are as follows-
1. Invitation letter (indicating just for visit - name different places/cities)
2. Letter to the consular (sponsor Letter)
3. My employment Letter
4. My bank Balance doc
5. Recent 2 Pay stubs
6. Last Year W2
Document your dad need to prepare--
1. Relation verification (show he has strong tie at back home)
2. Property valuation
3. Some bank balance
4. Leave letter from the office
5. Retirement Fund (if available) also works as bank balance
P.S. My dad's visa was also rejected at the first time back in 2007.
Let me know if you have any questions.