Mountain area?

Da Lat is the nearest one.
It's a lovely little hill station with panoramic view of the surrounding highlands and valleys. There are regular flights and bus services available from HCMC. Takes around 45 mints by air and roughly 8 hrs by bus. Plz google for more info.
The other two in that region (central highlands) are Buon Ma Thuot and Pleiku. These are less attractive destinations for regular tourists.

Yes I agree Da Lat is by far the best mountain retreat it's beautiful good weather and a lot to do and see

Thanks a lot Rihull and bia_hoi.

many moutain area near Ho Chi MInh city. U can go to:

Buu Long Moutain (it is a pleasure to review this nature reserve / park. About 1 hours from Ho Chi MInh city by car)

Black Virgin Mountain (Tay Ninh, Vietnam) (about 1 hours or 1 hours half from Ho Chi Minh city by car)

Jesus Statue & Vũng Tàu Lighthouse in Vung Tau Mountain (about 3 hours from Ho Chi Minh city by car)

and Da Lat is the good choice for a long trip ^^

Others mentioned Dalat, Lam Dong, which is a quaint romantic French Colonial style city. It's a vacation spot for Vietnamese and foreigners alike. I spend a few months in Dalat each year. There are recluse areas if this is what you seek or temples such as Truc Lan or Phuong Lam temple or romatic spots like the valley of Love...on Sundays Dalat Center is blocked off from traffic and lots of people are out walking around the center and around the lake.

If you take a sleep bus either Thanh Bui or the other when you arrive they'll transport you to your hotel or where your staying. The airport is far from the city and you'll pay extra to get to the city.

Vietnam has lots of mountains. it is about what you are looking for. Privacy, romance, sightseeing... Dalat has all of this.