Bangkok population 12 million vs KL 2 million. Furthermore Bangkok is a major airline hub. KLIA is stuck in between two of the biggest airline hubs in the world, Singapore and Bangkok. Honestly, everytime I use KLIA, I feel like being in a ghost airport cos nobody around. LCCT feels more like an airport to me.   
Depending on what u want to see. If you want to see only main tourist attractions, maybe 2-3 days in Hiroshima, 3-4 days in Osaka, 2-3 days in Kyoto and about a week in Tokyo. Honestly a month is quite a long time and you can visit almost all the major cities from Sapporo to Fukuoka is budget is not a problem.

Simple...if you go Europe or US not major City....Deep Country Side....those people know where is Thailand ..where is bangkok where is phuket Island......and where is Singapore......but they dunno where is malaysia....in their mind There is no malaysia exits.....malaysia still a place who everyone still live upper tree.