1. Good Route travelling to Vietnam, Laos, Cambodia and Thailand
Here's one example of a route you could try. With just 30 days, I'd suggest leaving Laos for another
trip.
Ho Chi Minh City - Cantho (for some of the largest floating markets in Vietnam)
Cantho - Chau Doc (More Delta stuff, boat to Phnom Penh)
Chau Doc - Phnom Penh (Sightseeing, relaxing by the river)
Phnom Penh - Siem Reap (Angkor Wat)
Siem Reap - Trat (Typical small Thai town)
Trat - Ko Chang/Ko Maak/Ko Kut (Three islands - take your pick!)
Trat - Ban Phe - Ko Samet (One more island just for good measure)
Ban Phe - Bangkok (Soak it up)
Bangkok - Kanchanaburi (Sightseeing, national parks)
Kanchanaburi - Sangkhlaburi (Temples, jungle scenery)
Sangkhlaburi - Bangkok