A couple of questions since you wrote modest.
What time of year?
How many nights?
What your actual budget?

Our budget is also modest... I guess about $4,000 per couple for accomodations up to 10 days.
Since out anniversary is January and our in-law's anniversary is May, last time we split the difference and went for MARCH.

I was going to say the Sibonne in Turks and Caicos until I read AI. It's a boutique hotel with 26 rooms on Grace Bay and close to a few restaurants.

For AI, I would say the Manchebo Beach Resort & Spa in Aruba. Adult only AI, boutique hotel with 71 rooms directly on an really nice section of beach.

I've always thought of Aruba as a college spring-break party spot... but the book that I got from AAA says that Aruba is among the friendliest of islands. I will definitely check that out. Thanks!

Whoa! What is the 20.5% tax rate about?
I don't remember a tax rate that high in Antigua, am I missing something? Service charges?

Not sure. I just go buy how the on-line booking agents charge for air/hotel packages. We haven't been back since out trip in 2006 because it has been too expensive. The AI hotels in Aruba charge 2 - 3 times more than I what I pay for AI's in Mexico and Jamaica. Many of the restaurants charge a service charge, which is in essence an automatic tip.

Going AI in Aruba is really not recommended. There are tons of great restaurants and bars in all price ranges. One of the experiences there is to try as many as you can.

No, I would not say Aruba is a "college spring break party" like Cancun. It is most frequented by families and mature couples.

AI in the Caribbean are few and far between except the DR, which I don't recommend to anyone because I don't like it, and Jamaica. Mexico has the best, least expensive AI's and tons of things to see and do off property.

A couple of issue I see is the word "modest". To me that means inexpensive. But, comparing to your trip Antigua, and your budget of $4,000 per couple, that's more than I usually spend on vacations. My limit is $3,000 for 2 with air for 6 - 7 nights AI.

March is the height of Spring/Easter break and high season, so you will tend to pay more than is you waited until May or June. You will find resorts full of families in March unless you choose an Adult only resort.

We are planning Barbados this year and for 6 nights it's coming in between $3,200 and $3,500 for November. We chose the first week of November since we have gone many places during that time and the child factor is usually less. Look at Mango Bay, Crystal Cove or Turtle Beach. All AI properties.

Thanks!
Obviously, I am an inexperienced traveler, celebrating my 30th wedding anniversary with my SECOND caribbean trip... I appreciate any and all travel tips! The tax at Manchebo puts a 10-day, AI per couple cost over $5,000! I'll check out your other suggestions too. Thanks!

And, that is why we have not returned to Aruba, though I want to so badly.

just some thoughts:
http://www.coyaba.com/ grenada

http://www.turtlebeachresortbarbados.com/
http://www.mangobaybarbados.com/en/welcome.php

http://www.capesantamaria.com/ bahamas, long island. not strictly ai but offers full meal plan.

Thanks for the ideas! Beautiful resorts but way above my budget!
SO SAD that I don't have more money to spend on these beautiful resorts!
I think Coyaba may be my favorite, but came out to USD $7,320 for the same AI 10-day stay!
Turtle beach appears to be USD $7,390.00
Mango Bay is USD $820 per night for an ocean front room
Cape Santa Maria is cheaper at $587 per night per couple with a meal plan. Children under 12 free, which means lots of children. I love children, but on my anniversary vacation I would prefer to be childless and carefree.

sorry laurie i thought your budget was for 7 days... plus i used the least expensive rooms as my base. and yes it is sad that the caribbean is so terribly expensive. i so hoped it would get cheaper when the economy tanked - figuring fewer travelers would make prices lower but i think it's had the opposite affect.

how do you feel about maya riviera coast in mexico? (from cancun south to tulum) there are a few adult only ai's - kvr would know more about these than i do...

Here is a list of AI resorts in the Caribbean.

http://www.caribbeanallinclusive.com/caribbean_all_inclusive_resorts.cfm

I really couldn't find anything that would meet your budget and criteria for 10 days, especially if you're wanting the highest catagory beachfront rooms. You might look at Couples Negril or Sunset at the Palms in Negril, which is not beachfront, but across the street from the beach.

Here is a list of AI resorts in Mexico:

http://www.mexicoallinclusive.com/mexico_all-inclusive_resorts.cfm

Most of the AI resorts will not be "boutique". Look at the Mahekal Beach Resort. Little cottages on the beach with no TV or phones. About a 20 minute walk to 5th Avenue in Playa del Carmen. They include breakfast and either lunch or dinner, but no alcohol.

The Akumel Beach Resort in Mexico, but it allows children, so if you go in March it will be full of families.

Maybe the Eldorado Maroma Beach if you go with the lowest catagory room. It's an adult only AI.

You might have to compromise somewhere. Either increase the budget, stay less days, choose the basic level rooms or go when it's not high season to get more for your money.

Catalonia Royal Tulum in Mexico would fit you needs except for being walking distance to a "town". It's an adults only all inclusive resort on one of the most beautiful beaches. Not a big mega resort.

I agree with the suggestion of looking to the Mayan Riviera in Mexico (the Caribbean coast flying into Cancun then heading south). You get a lot more bang for your buck there than on the Caribbean islands. Also there are many All-Inclusive properties to choose from.

Don't let the taxes scare you off, in Mexico it's 18.5% I believe on hotel rooms. Usually it's just figured into the overall rate so you don't see it separately.

I know it has been awhile but my husband and I stayed at the adult only Almond Beach Club in Barbados. It seemed pretty reasonably priced back when we went. We had a great time. We only stayed a week, ten days might be a lot more. I just thought you might want to check it out

Oh I forgot to add that it was AI and that included alcohol

I just checked the rates online, and for a week with a flight from Portland, Oregon(I don't know where you are coming from but that's where I am) for a week it was $3200(including air)and for 10 days it was $4400. Thought that would give you an idea, if you are closer than I am to the Caribbean then it might be less.

Another strategy would be to drop the trip to 7 instead of 10 days, to get a nicer resort for the same amount of money.

I did look at the Mayan Riviera, but couldn't seem to find a small AI resort within our price range... but I did check back at the Coconut Beach Club in Antigua and they have a special for return guests I think we may just go back there... we know what to expect and its a great deal for the 2 bedroom suite!