Greetings Nate:
The wonderful thing about veneer quality trees is that the per unit price ($/bd ft) generally increases as diameter increases, i.e., a 20” DBH black walnut with four sides clear (4SC) might be worth $3.00/bd ft whereas a 28” DBH black walnut with 4SC might be worth $8.00/bd ft. These prices, of course, are used as examples and do not necessarily reflect current pricing. There are, of course, always exceptions. Trees which produce false heartwood, such as ash and hard maple, are sometimes more valuable in the smaller diameter class (18-22” DBH) because of the smaller percentage of false heartwood.
Based on my conversations with veneer buyers, a premium is usually paid for logs with low sap content (trees harvested during the dormant season). However, it should be noted that veneer prices are driven by foreign and domestic markets – if markets are up, prices are up; if markets are down, prices are down. Therefore, prices paid in October through early February usually command higher prices due to lower sap content. It is important to note that most veneer mills have their own standards and specifications. Some mills might accept logs with DIB’s of 14” whereas other veneer mills require logs with DIB’s of 16” [DIB is “diameter inside bark” at the small end of the log]. Therefore, this generally means that you need to grow your trees to a minimum of 16-20” DBH.
Here is a good publication from Purdue University on Veneer Attributes for Central Hardwood Species:
http://www.ces.purdue.edu/extmedia/FNR/FNR-239.pdf
Regarding which tree species to plant on your hillside -- let your soil types dictate which species you should plant. Here in Illinois, red oaks, black walnut, and black cherry will have faster growth rates than white oaks. Depending on your soils and site, you might be able to produce merchantable timber in 40-60 years. Contact your local Farm Service Agency office to get a soil map of your property. From that map, you will be able to identify the soils types on the hillside. From this information, your local DNR District Forester can give you advice on planting trees suitable for your soil types.
DNR Forestry Offices: http://dnr.state.il.us/conservation/forestry/
Farm Service Agency Offices:
http://offices.sc.egov.usda.gov/locator/app?state=IL&agency=fsa
Best of luck and thanks for the questions!