From Boston? Florida comes to mind for 3-4 days. Bahamas or Bermuda outside the US.

I've only been to Disney years prior. Where in Florida would you suggest?

Caribbean Islands safest to guarantee warm temperatures,Virgin Isalnds, Puerto Rico, and south.
Florida can be warm or have a cold spell. I had to buy a coat there once when visiting in March.
Bahamas
Too early in the season for Bermuda.

I not that familiar with Florida beaches and resorts, but I am sure there are many posts on that subject. How about Key West or a resort near Naples/Tampa?

My friend has been and didn't care for Puerto Rico. Virgin Islands could be worth some investigation.

Bermuda is one of my favorite places...too bad it's early

Naples, Miami Beach, Key Biscayne (Miami), Key West (but travel time a problem for such a short break).

February is warmer than January, March is warmer than February. By April it is hot. But it won't be cold any of that time.

The problem with the Caribbean is transiting thru Miami. It is a great destination but a terrible place to change planes, especially returning. Look into direct flights from Boston if you must go to one of the islands.

Get a direct flight to Tampa and drive to Sarasota!

What is Sarasota like?

Sarasota is great. Fun city, good restaurants, gorgeous beaches and shopping. What's not to love? Personally if I were going over a weekend which wasn't a spring break time I would pick up a rental car in Sarasota or Tampa and take my chances on finding lodging which appeals to you and your companion. I like Lido http://www.lidobeachresort.com/ but there are a lot of choices in the area. Have fun. I love Boston and Bermuda....but not in March!!!

St. Petersburg is lovely with big wide sandy beaches. We also love Captiva/Sanibel Islands. Very laid back and relaxing.

I used to know someone with a holiday home on Sanibel island. I was under the impression it was somewhat of a "retired" community.

Just got back from Key West, with a little time in Hollywood and Fort Lauderdale, Florida. All excellent -- the sunshine down in Key West felt fabulous!

If you go in Jan or even Feb you might not get beach weather in FL. For that head to the Carib - or wait until March?

For Boston - are you wearing clothing that is warm enough? (We had a niece visit from FL and she thought she would be warm enough in jeans, a sweater and medium weight coat. We had to take her shopping for cords, thick sweater, long-sleeve shirts, a winter coat (to 20 below), warm socks and lined boots with a sole that kept her off the sidewalk. When it's zero, damp and windy at night - it's very cold.)

Go to the Ibex store on Newbury St. Fantastic cold weather clothes!

Coming back after 4 days away to temperatures 20-30 degrees colder than when you left will be so much worse.
Get yourself a coat and maybe the heated boots if you have to live in Boston through the winter. http://www.columbia.com/Omni-Heat%C2%AE-Reflective-Gear/Collection_Omni-Heat_Reflective,default,pg.html
What you save by not taking the trip is best spent on some gear that will keep you warm all winter.

Echoing nytraveler on two points:
Sarasota is not reliably beach warm until late February. There will be lots of warm weather but it won't be reliable.

Dressing warmly: my dear wife came north to college and walked around the first winter in a raincoat and tennis shoes. She didn't know it was _possible_ to be warm so she accepted being cold. She learned.

New thought: if you only have 3 or 4 days, what do you do when there are travel delays? Are you SOL or is your time flexible? If you go somewhere expensive, get trip insurance because they may not give you a refund if you have travel delays.

don't worry... "colduphere" lives in Canada and the border patrol has an eye on him...

You can transit through San Juan for the USVI, not through Miami (which is a mess). But if you're traveling internationally into the Caribbean, see what you can do to avoid Miami.

I've lived in Boston, including through a winter; I live in Dallas County. I'd NEVER choose to live in Boston again.

Even though Florida and Puerto Rico and such are not ``beach warm'' you will probably find them ``spring day warm'', i.e. sun and breeze and ok for walking outside with maybe a light jacket. That may be enough to tide you over -- if its all you can afford, go for it, but only if you can handle the possibility of imperfect sunshine.

If you are really looking to bask, think southernmost part of the Carribbean.

In January/February in New England you will see tons of advertisements for getaway trips to sunny places (go figure) -- keep an eye out for good package deals, but do be skeptical and check the hotel ratings: Sometimes the fabulous deal involves a nasty room in an unhappy location.

Also, it may help to know that that reee-diculously early nightfall you are currently experiencing (I live in western MA) will not last all winter -- you will see improvements in daylight hours by Christmas, I promise.

More advice: Get a warm hat and wooly socks, and wear them all the time, even indoors. Consider getting one of those all spectrum light-boxes and sit before it at breakfast each day. Think about embracing the winter via ice skating, snowshowing or skiing. Hang in there..

Look at these average high temps for Sarasota, http://www.sarasotadowntown.com/temperature.html. It's true you could hit a cool spot, but odds are better that you would not, and "everything is relative". I see people swimming year round here as far north as Clearwater Beach, but you can bet they are from elsewhere! The earliest I've been in is early April. I love Sarasota and the entire string of barrier islands from Longboat Key up to Anna Maria Island. Each has a different flavor depending on how upscale you want to get. We live in St Pete which also has beautiful beaches and a vibrant downtown.

The joy of this area for tourists is that there are a lot of airlines with direct flights into Tampa and its a easy drive from there to all the Sarasota/St Pete area. I totally agree with everyone on the Miami airport. It's the absolute worst airport I've ever had the displeasure of flying through!

Capxx has a good point about embracing a winter sport. Dress for the cold and you'll be fine. I grew up in the Berkshires with a ski area 5 minutes from my house. I absolutely hated to see winter and the ski season end. Moved away after college and were transferred back to Boston after living in New Orleans. The cold was tough to take after New Orleans, and with two toddlers and a southern husband, skiing was no longer in the mix. All I could think about was getting out of there, and with his job we knew we could at any time we wished. So instead of embracing the area, which is beautiful and just loaded with things to do, I thought nothing but escape. I don't recommend that approach! We were transferred again 16 months later to Dallas and I never looked back, though I'm the first to admit, there is much I miss about New England..

So plan your getaways, but embrace what you have too, knowing that late spring, summer and fall are glorious, and you'll no longer face strings of 100+ days. In your shoes I'd try to plan a late February or early March getaway. That's the time you'll be so over the snow and slush and gloomy days, and odds of gorgeous weather here are much improved.

I don't think there are enough clothes in the world to keep me warm in a midwest winter. I hate the cold. Just returned from a month in Central America, and I'm miserable. And, it's above freezing at the moment.

The new year can't come soon enough. I'll be fleeing back to the warmth of Central America.

That said, the OP might be able to find find cheap packages to Cancun for the long weekend.

That is not a bad idea--Cancun, I mean, as JetBlue flies a non-stop, or at least they did in 2010 when we went down for a wedding. It was early December and downright balmy there!

I was going to say fly nonstop into Cancun, and take the 1st class bus from airport to Playa Del Carmen ($10). Stay on or close to the beach. Your money will go further down there. Great place to celebrate a birthday.

Yes, the wedding we went to was actually in Playa del Carmen. Gorgeous beach and water!