For post-wedding honeymoon people look for romantic getaway. Especially if you are exhausted after months of preparatory work and big banquets, just sitting back at a quiet resort will be a good treatment.
An engagement trip can be more adventurous. A road trip will provide different shooting locations and your photo book will have a more professional taste. I would suggest a itinerary with a combination of nature and vividly-colored cities.
Engagement photos are better to look like snapshots of daily life, but a little thought will produce better results. Bring several set of clothes with different tones. Avoid loud patterns. Makes sure your clothes get along with your partner's. Don't try to wear only brand new clothes, and avoid wearing hats you never wear: the resulting photos will not look like you.
After all, having fun is the most important factor for happy photos. Have a pleasant trip!