I made a relot of all stages of the Maxis seaport. No more just an ugly pier, but an in-land functional spaceport.
(https://www.sc4devotion.com/forums/proxy.php?request=http%3A%2F%2Fimg267.imageshack.us%2Fimg267%2F5371%2Fnewcity4jan001329055040.jpg&hash=be47d09c2d6cc376907afdcc907ac45a0497df3d)
In stage 1, the spaceport will home 2 small air vessels. Those vehicles use jet and rocket engines for vertical take over and land and are suitable for interregional transportation. The stage 2 will home 2 medium vessels, with better engines and enough fuels for orbital flights. They can dock on orbital colonies and even visit the Moon. The stage 3 is mostly underground and can home a huge spacecraft, special design for interplanetary flight. You can finally ship your products to Mars and other farther colonies.
(https://www.sc4devotion.com/forums/proxy.php?request=http%3A%2F%2Fimg843.imageshack.us%2Fimg843%2F3715%2Fnewcity4jan001329055067.jpg&hash=6a4024a1b50d3faf6bcc08ed00faea6690c0d0eb)
(https://www.sc4devotion.com/forums/proxy.php?request=http%3A%2F%2Fimg713.imageshack.us%2Fimg713%2F9828%2Fnewcity4jan001329055081.jpg&hash=929d4f83e38c05b36ef3c2daa2f3f20236ad72eb)
(https://www.sc4devotion.com/forums/proxy.php?request=http%3A%2F%2Fimg580.imageshack.us%2Fimg580%2F5586%2Fnewcity4jan001329055093.jpg&hash=c7196116deb4c4a869ddfce6b28bc80fbd3f4bdc)
Notice 2 small gaps with the roads in every stage? Those gaps means that you can place a single spaceport... or 2 of them! The fence will not surround the whole spaceport, so you can build 2 of them and make a larger one.
(https://www.sc4devotion.com/forums/proxy.php?request=http%3A%2F%2Fimg826.imageshack.us%2Fimg826%2F1890%2Fspaceports.jpg&hash=93bf7afa563160606965e94a833cabe6c6b5b523)
However there are 2 problems and I need some help please. The game refuse to upgrade the spaceport, no matter what ()sad()
(https://www.sc4devotion.com/forums/proxy.php?request=http%3A%2F%2Fimg806.imageshack.us%2Fimg806%2F4381%2Fnewcity7oct131329053923.jpg&hash=6451984702dc41dd93eb051ccf9e34589174da38)
It's also possible to build the third stage directly from the menu, but it doesn't have any capacity. A useless sitting duck ()sad()
(https://www.sc4devotion.com/forums/proxy.php?request=http%3A%2F%2Fimg190.imageshack.us%2Fimg190%2F9715%2Fnewcity29jan01132904911.jpg&hash=48bce7fbeaeed75ace611d2df16eea49ebb7fc83)
Is there a problem with reloting the Maxis seaport? Is the stage upgrading chain broken? &mmm
I think I remember seeing this on your lotting thread, but forgot to post anything. Are you sure you have seaport upgrading enabled? SC4 doesn't upgrade them by default, you need to have a file that makes this change in your plugins, such as X-Ports Automatic Upgrade.dat from either the AC Functional Airports or BSC Functional Seaports (they use the same file).
If you do have that, and the seaport still won't upgrade, I'd build a sandbox city, toss some of the BSC Functional Seaports or the AC Prefab Airport in there, run it for a while, and see if they upgrade (a medium sized city heavy on the industry will be enough to force seaport upgrades quickly).
If everything else works fine, and the only thing that refuses to upgrade is this seaport, then I'd think something about the lot is causing the problem. At least then you know where to focus your efforts.
You might also find this post (http://sc4devotion.com/forums/index.php?topic=7138.msg227125#msg227125) useful if it isn't how you're already going about making the seaport.