Haoi
In Hanoi, I suggest to go one evening to the "Water Puppet Theatre" near the central lake. There are 3 shows/evening, lasts about 1 hour and costs 20000d/50000d-front seats.

From Hanoi I took the train (soft sleeper, A/C 390 000d) to Hue, overnight train. Hue, cyclo to guest house-area, 5000d. GH 35000d /dorm bed - but if not many guests you can get a room for 30000d. Visited citadel (over priced at 50 000d for foreigners), walking in town.

Hue
From Hue I took tourist bus "open bus" to Hoi An 20000d

Hoi An
Nice old town.
Hotel 45000/dorm bed - there is no cheaper option in HoiAn. Many tourists, lot of hassle and verbal harassment from vendors/tailor shops/moto-drivers. More quiet if you go early morning (before 7am)- then you can enjoy walking in the town. They try to collect 75000d(!!!) ticket for the "old streets" and this include visiting 5 of the pagodas/museums, too. I did not buy ticket - I find it ridiculous to pay for walking in the city - and was never asked by the ticket collectors. They usually want to see your ticket only at the museums/pagodas and the "Japanese Bridge" - but you can see in free in the early morning.

From Hoi An I wanted to go to Qui Nhon. I went to the local bus station to take a bus to Danang. The guy of the bus wanted to charge me 4 times of the price. He refused to let me on the bus because I refused to be overcharged. So I took the next bus, also there they tried to collect 10000 instead of 5000 but some old ladies encouraged me just to hand them 5000d. In Danang we arrived to a bus station 500m from the long-distance bus station. There I bought my ticket to Qui Nhon (65000d) without any hassle - the ticket prices are written clearly at the counter - there is no discrimination against foreigners)

Arrived at Qui Nhon around 6:30 pm. At bus station they could not give info about buses to Nha Trang... They said I have to pay the ticket until Saigon, and get off on the highway-turn off to Nha Trang. I went to the only backpackers' place: Barbara's GH. No dorm. Overpriced rooms (80 000d) with nice beds but ugly run-down bathroom with cold shower only. I checked several other hotels, but all were more expensive (but nicer, too).
Riverfront is nice, there is a cafe in front of Barbara's GH by the river, with local prices.
Qui Nhon is not touristy, nothing special quiet nice little town. I wanted to go to nearby hot spa - but could not get info about it (i.e. if I can take a bath in an open-air natural pool or not) and also could not learn about public transportation so I gave up the idea of going there.

From QN I took the local train (39000d) to Nha Trang (6h).
Nha Trang from the r.s. walking to GH, 30000/dorm bed, nice Korean/Vietnamese couple runs the GH.

NOTE: In Vietnam, many GH/restaurants have VERY similar names. It is because if one place gets popular and it is listed in a guidebook, other places try to grab their customers by cheating and having a similar/sometimes even the same/ name.

Nha Trang
Nice beach.From Nha Trang I took the tourist bus to Mui Ne (75000d) Arrived at Mui Ne around 2 pm

Mui Ne
Mui Ne is an insignificant village, before the village for kilometers along the road there are the Guest Houses and "resorts" by the beach (the road runs parallel to the beach ).Stayed at a bungalow-room for 60000d.