Sure. The most active repeaters for general chat stuff are 147.39 and 146.91 (Broken Arrow).
Also active and heavily used for storm spotting is 146.88 and the W5IAS linked system - 443.85 is the Tulsa node of that system.
There is also some traffic on a number of other repeaters - 147.045 and 146.805 are probably next in line for activity. The backup repeaters and the ones in the outlying areas are generally less used, but there are a couple that have a bunch of die-hard users. 147.06 in Pryor and 147.09 in Claremore are pretty active, but can be hard to hear in Tulsa depending on your location and antenna. If you're interested in a particular direction let us know, and we can get your more freqs.
Also check out the club web sites to get repeater lists (and updates on their status - several are down for maintenance at the moment)
Of course, it is possible to put one up without coordination, but all the major ones will be there. Don't be too surprised if you never hear anything on some, there have been a lot of "paper repeaters" that either never got put up or failed and weren't fixed - although ORSI has been putting forth some effort to clean those up recently.
And simplex can be used fairly often - just a matter of local convention where, but you could do a limit scan through the simplex areas of the band plan. The following has a good breakdown of what you'll find where on the various bands: Band Plan
Most likely for VHF (which tends to be the most commonly used "local" band) would be the 146.40 - 146.58 range, although any can be used.