Rohnert Park has roughly the same number of vacant apartments as the national average. As a result, you'll find that you need about two to three months to find an apartment in most cases. Summer is the best time to look, as you'll have more vacancies and less people actively looking for a new place.
Finding a larger place and bringing some roommates with you is in your best interests when shopping for an apartment in Rohnert Park. Unless you have a high paying job or have strong financial resources, landlords will wonder about your ability to pay for a one-bedroom apartment on your own. With roommates, rent payments don't seem so daunting.
Sonoma Country Transit and Golden Gate Transit both have busses that run through Rohnert Park. If the bus isn't for you, then you'll probably want to have a car here. However, if you don't mind getting wet occasionally in the rain, a bicycle can also be a great way to navigate the city. There are enough cyclists here that the roads are fairly bike friendly.
The climate makes Rohnert Park and the surrounding area perfectly suited for outdoor recreation. Excellent golf is available at the Foxtail golf courses. There are also outdoor tennis courts and soccer pitches available for the public to use. If you do have a car, taking a trip out to the Sonoma or Napa Valley wineries will show you what this part of the country is most famous for.