With a new flat there are a great number of possibilities depending on where you place it, what it replaces, whether capacity comes before ride experience, etc...
Now, straight off, as a family ride with a good capacity, and also a fairly unique one I wouldn't mind one of these - [url=http://www.youtube.com/watch?v=uhLnK-meJ50" onclick="window.open(this.href);return false;]http://www.youtube.com/watch?v=uhLnK-meJ50[/url] (unfortunately the video quality is terrible).
You sit in an Air style, flying position, before flying around in a Twirling Toadstool type way. Too similar to Twirling Toadstool, perhaps, but a good family attraction with a high capacity it is, and I think it would make a nice addition to the park, potentially on The Beastie site?
Of course, as more of a thrill seeker myself, I can't really resist throwing the Robo-Arm concept into the mix, unfortunately these would be painfully low capacity, such that Alton Towers would have to install 10-12 of them just to keep queues down to an hour or two, so I think the only way we're going to see one installed is as an 'additional charge' attraction, and I certainly don't want to go down that route.
Ideal for the UG Swinger site were it not such low capacity, no?
Moving into X-Sector, where Alton are likely to get away with building slightly taller rides. Looking at the area, Enterprise and Submission are both ready to go, what should replace them? I suppose I'd have to go with a Top Scan, personally, but again the God awful capacity of these fairground rides would mean queues of 2 hours or so on busier days (see Samurai's Thorpe Park), and I reckon we'd see a lot of down-time.
So possibly 2 Top Scans, one for the submission site and one for the enterprise site? I see that as a plan, though I'm not 100% sure that they'd both fit.
Next? Black hole tent. A permanent scare maze? As much as I'd love to see it I don't think there's any chance of it happening, and again, throughput would be dreadful! How about a Mega Disk'O? It would surely fit, and could be turned into a pretty impressive ride if themed appropriately?
Finally, Forbidden Valley, where Blade surely needs a replacement. Again, that Mega Disk'O that I brought up earlier could come in handy, it would fit into the Valley nicely, providing a reasonable thrill whilst staying a family attraction. Alternatively, one of those weird vertical things that have opened as part of the new Toy Story area at Disneyland Paris wouldn't be bad.
Personally, I really think Ripsaw should stay, so I'm not going to even touch on that location. Personally, there are other flats that I'd be more than happy seeing at the Alton Towers Resort, Dynamo has been sorely missed and a similar ride for... well... the Dynamo site would be nice. I wouldn't mind seeing a Twister either, or a proper Pirate Ship built on the water in front of The Flume. A Sea storm ride for Mutiny Bay, is another possibility, or, I'd actually swap Heave Ho & Marauders Mayhem for a Mack Sea Storm and Twist 'n' Splash, without a second thought.
There really are so many routes that Alton can go down, as far as flats are concerned, and they need to take one really, and soon. Because the park is sorely lacking in the flats department.