Generally the hotels in Yangon are quite pricy compare to other countries in Southeast Asia due to the scarce number of hotels in Myanmar.
Since the national isolation policy has been lifted Myanmar has been attracting the businesses around the world. There are significant number of visitors has been recently recorded and there are not enough hotels to accommodate them.
Apparently there are 200 hotels with 8000 rooms in Yangon; however the hotels which are facilitated to accommodate foreigners are limited to 100 hotels. (according to statistic in 2013)
Currently there are also lack of 4 stars plus hotels in Myanmar.
A process of making reservation is still primitive in Myanmar as the direct website reservation is not quite popular and is not well received at this point.
Calling in directly or email request are sometimes necessary; however foreign investment company hotels such as Agoda and Expedia are accessible in Myanmar despite of the disadvantage in advance payment.
Either way, it is strongly recommended to reconfirm the reservation prior to arriving to the hotel as there may be a concern of double booking.
It is also strongly recommended to make a reservation through reliable Travel agency in case of problem. Usually the Travel agency is able to resolve the problem on behalf of client.