However, beware the danger of ending up with your business fundamentally built on Access. Many products make it easy to program, there is no product that makes programming easy. Just underneath the candy shell, the horrifying Turing chaos waits for you the same as any "real" programming environment, and many is the person who has inadvertently released an Elder God from his tasty confectionery prison to consume their business whole.
I'm being a bit flowery, but I am serious. It's happened many times and I've seen it myself once. Use the tool responsibly; the poky bits haven't been taken out, just moved around a bit.
1. Design your GUI using Interface Builder
2. Design your Core Data model in Xcode.
3. Connect the two using Bindings in Interface Builder.
You should hire someone smart to do this work for you, instead of trying to do it by yourself. Given that your requirements are vague, I would recommend you pay someone a few hundred quid/dollars to talk to you for a day and figure out what technology you're going to need to use. Then you will be in a good position to hire.
If you try and do this by yourself there is a very high chance you will do it wrong. Worst case scenario is that you don't even know it's wrong and it just keeps giving you the wrong data forever.
I worked with an insurance client once who had been overpaying bonuses for years without knowing. You don't want to be that person - hire a programmer. They are cheap, all things considered!
Also, I recommend trying out a hosted wiki and Google Docs. Having a shared Google Docs spreadsheet will probably be more functional than anything you can build without actually programming.
Meanwhile, you need to think about why people like spreadsheets. Yes, they show you all your data on a big stupid sheet and force you to look at it, but that's a feature, not a bug. People don't collect data because pressing buttons is fun. They want to see their data again. Indeed, not being able to relocate their hard-won data is their worst nightmare, so it is reassuring to see it right there and know that you can find it. It's easy to find data in a spreadsheet: Just scroll around until you see it. It's got to be right there on the page: It's a spreadsheet. Even a nonprogrammer can navigate a simple spreadsheet.
It's even easy to change the data. You see a number you don't like, you type over it.
If you want something with better organization or navigation than a simple spreadsheet, you'll need, at the very least: Forms to type the data in, and reports to get the data out. But presumably your forms will need carefully-chosen field types, and validation against app-specific criteria, and maybe even record-to-record relations, or why wouldn't you just use a spreadsheet? And the reports will have to be fancier than just a big table, or why wouldn't you just use a spreadsheet? And when you design these forms and records and relations and reports... you'll be programming.
1) The main body of the data should fit on one page. In many cases, it can be made to fit, you just need to reorganize some of it and tweak sizes of boxes, use some reasonable abbreviations, etc.
2) Try to keep it to 7 colors (though this rule can be bent a smidgeon by going one shade darker for emphasis without really introducing a totally new color).
3) "Whiting out" (though beige, gray or taupe can be better choices than white) the background boxes can go a long way towards making a spreadsheet less torturous to look at.
4) Going one font size up and adding bolding can be plenty of emphasis. You really don't need anything of size 72 lettering just because it's a title or some such.
(I'm sure you don't personally care. And I'm not trying to change your mind. Maybe I just needed to say it for myself.)