There are probably quite few places which offer the same opportunities. Vietnam combined both conventional and guerrilla warfare, as well as hard limits on how much the US could escalate it, relating to the risk that an invasion of North Vietnam would bring in China. There are few other states which border directly, and which are zones for such violence, the Communist world. It has to be on the border of the USSR, direct overland USSR puppets, and China, or else the USA would be able to apply overwhelming force and destroy it. Preferably it will also have a state with proven nationalist credentials and victories under their belt, as well as being proved as having mettle for war - as Ho Chi Minh's Vietnam did. Preferably it will also be part of a battle for influence between the USSR and China, which had both of the Communist great powers trying to upstage the other in winning a puppet or containing the other side.
The US was able to ultimately defeat and constrain the risk of guerrilla warfare. Look at a chart of guerrillas in Vietnam at the beginning and by the end of the American intervention - they had been dramatically reduced and the Americans had essentially beaten the guerrilla warfare risk. The problem was that ultimately North Vietnam was able to engage in conventional warfare by its excellent army, which decisively crushed South Vietnam's regime. Other regions, like South America, most of Africa, anywhere not bordering the Soviet Union and China, are ultimately places where the US
will win, in conjunction with the local regime. It will be bloody, it will be unpopular, but the US will smash guerrilla forces to a sufficient extent that the war becomes a non-issue, and that it can leave and provide enough support to the remaining government without popularity reaching critical mass problems internally. If it is a question of conventional warfare, the US can destroy any state with a direct invasion. There are few OTL examples of states combining both the highly competent and effective Vietnamese People's Army, with a powerful guerrilla element, and the inability for the US to stamp out the bases of power of the guerrillas.
I would say that the closest that you might get to this is Iran, with difficult geography, a society which has proven capable of fighting a competent war as an organized army (to the stark difference of most Arab nations whose conventional forces have been disastrous), possibility of supply from the USSR, the inability for the US to intervene in northern Iran, and the possibility for significant guerrilla operations in southern Iran.
Honestly, it seems like the internationalized Algerian War is the best candidate.
Algeria has:
- Urban and mountainous terrain that have already seen guerrilla warfare.
- A close link to Nasserist Egypt and Libya, which can easily provide supplies, airbases and potential sanctuaries while staying out of the war.
- A determined army and guerrilla movement that are proud of their independence and will fight to preserve it.
- Capability to have both a strong, rigorously-trained militia movement and a proper army in the fight.
- An ethnic minority that will willingly help the foreign army invading and will be brutally persecuted postwar because of their assistance.
- A battlefield that has already beaten and booted out the French in a war of attrition.
- Potential for the foreign army to realize that they're fighting against people who just want independence, and while their government is Soviet-aligned, they are not a direct threat to their home nation at all.
- Caused massive protests OTL, and will cause massive protests ITTL.
Sure, the jungle warfare might not be there, and napalm will be of little use in North Africa's less dense foliage, but otherwise, all the boxes are ticked.
The problem is that the French on their own were able to
militarily defeat the Algerian rebellion, which the American army with its much larger forces could do as well. Egypt and Libya will have much more trouble shipping in supplies and supporting a rebellion. But the worst of all is that unlike in Vietnam there is no conventional army to ultimately deliver the killing blow - the US will funnel in troops, suppress the rebels to an acceptable extent, then withdraw, without the ability for the rebels to still have a win game. There won't be the combination of rebel strengths to make the war so deeply impossible and unwinnable for the Americans.