I am not too sure about how your school determines your rotations, but really, a mix of the two types is just about perfect. Let's face it, you are going to have to be able to get along on the wards to be a successful intern, and the experience you get as a med student is a big part of that.
1. There is burnout in everything, especially when you work hard. The burnout of third year may be that you have finished many of your required rotations, you still have no idea what you are going to do and decision time comes up too fast, and you are just plain tired. You have Boards to look forward to (yay! the comlex! where's my gun?) and then people just telling you how much better/worse/the same 4th year is. At the same time you want to be a doctor, you know you're not ready.
2. Part of getting along with all the ancillary staff is understanding that they didn't necessarily sign up for the "teach a new group of students every month" club. Their jobs are not easy and sometimes the student can make it even harder. Remember that there is no law against saying good morning/hello/how are you/hope you have a good weekend to anyone.
3.The advantage to office/clinic based is that you have more attention from the preceptor and see more ambulatory care, which allows you to practice your physical exams skills and coming up with assessment and plans. The advantage to the hospital is that you see the acute/sick/injured patient and get practice in management and working with a team. Always remember that everyone's job is important - we ALL work together to take care of these people.
Above all, remember to look forward to your clerkships. The most important thing you might learn is how glad you are that there are people who want to do things like xyz for their profession. Third year is likely the first time you get to really feel like you are learning what you need to know to be a good clinician. There is learning every day.