If RFG called his girlfriend his cell phone would have pinged a certain tower. Has that info ever been made public? I may not understand how pinging works exactly, but I've seen references to it here on other cases so thought it worth mentioning. Sorry if this has been covered already.
Here are my thoughts for whatever they're worth. According to the info on the case, RFG didn't like cigarette ashes in his car, but I'm wondering, was there ever a time in his life when he himself smoked?
Regarding suicide in families:
http://www.healthyplace.com/depression/articles/suicide-risk-runs-in-families/
Not saying RFG committed suicide, but it seems likely some kind of planning took place towards some end, either suicide or disappearing. Taking his computer, but not its case or charger raises questions in my mind. Laptops are fragile, one drop, and poof, there goes the laptop. If his excursion started out as an innocent short trip, it just seems likely the laptop would have been taken in its case.
What is known about the incidence of depression or other mental issues with RFG and other family members? I do think suicide is a distinct possibility in that RFG's daughter has never been contacted by him and with his brother having committed suicide in 1996.
I wonder when was the last time RFG and his daughter were in contact?
Someone entertaining thoughts of suicide is quite likely to distance him or herself emotionally from family and close friends leading up to actual suicide.
Did RFG try to make his suicide (a supposition) look like foul play? He most definitely would have been aware of the devastating effects of suicide on those left behind after his own brother's suicide. From experience, I know the self-questioning and self-blaming that goes on in a family when a family member commits suicide, but if loved ones thought foul play instead, it might at least spare them the devastating anguish a suicide can bring. I somehow doubt RFG's loved ones really think his death was caused by foul play. There's not enough solid evidence to convince, an a prior suicide in his immediate family suggests otherwise, at least to me.