If I were you, I'd make this really interesting, since you will most likely be aging in 5 or 6 gallon carboys, you can oak some, and leave some unoaked, giving you two distinctly different wines!
I'd personally use oak infusion spirals, they impart the oak much slower than oak chips, with oak chips, it is easy to over oak a wine as they impart all of their oak flavors within a day or so. With the Spirals, you can taste the wine over a few days and decide what level of oak you prefer, just remember, oak tends to dissipate over time so don't be afraid to slightly over oak.
I'd use medium toast, it is a nice safe level of toast.
a bit off topic but if you plan on fermenting in 2 different batches, you could ferment with different yeasts as well, the wines would have different characteristics, and levels of complexities, I wish that I was doing this!!!!!!!!!!!
Let us know what you decide!