"I think it would be great." "I think it's going to be great." "I think it'll be great."

What about I drive you home first? I think it would be great.
先把你送回家怎么样? 很好

What should we do with such a situation? We can handle and I think it's going to be great.
这样的话我们怎么办呢? 我们可以处理, 一切都会好起来的.

How do you think about our coming show? I think it'll be great.
你觉得我们即将开始的展会怎么样? 一定非常不错.

其实都是非常口语化的, 区别就是用的场合不同. 但是有一点请切记, 英语和中文一样, 不要总用" I think 我认为, 我觉得"开头, 可能会给别人太主观的感觉, 可能会让别人感觉不舒服.

Actually they don't have much differences. Say with it whatever you like.

"I think it would be great."
这个的意思是,我想它会很好,可是只是我想,但是它实际上可能并不好.

"I think it's going to be great."
"I think it'll be great."
两句意思一样.都是将来时,可以实现的.

其实他们没有什么多大的差别，只是不同的人讲得不一样而已，不过第一句话会更加口语化一些。