I work for a pest and termite company so maybe I can answer some of these questions.
Monthly pest service is usually recommended for clients with difficult problems that require more follow up. If your company has you on a monthly frequency it may be due to that. If they told you they need to come out more often because of rain, they may not have access to the proper products. We have many different products for all weather conditions that all have a residual life of three months.
As for termite service, you need to look at the guarantee and products being used. Not all products are created equally and some baiting systems are not as effective. Be sure if baiting you are getting sentricon with recruit HD; it's an always active system that offers a greater success rate for prevention. Also, the guarantee in case of failure: be sure of what you're getting into. Many companies exclude hardwood floors and personal possessions. Some guarantees have terms that limit your rights as customers also.
If you live in the Southeast, see if Massey services is in your area. We do no cost inspections and consultations.