Book now: United opens the Europe saver award floodgates

While we're still waiting on some much-needed details, the European Commission has confirmed plans for the European Union to open to vaccinated Americans this summer, potentially making countries like France, Germany and Italy accessible to U.S. tourists for the first time since March 2020.

A handful of European countries have already begun opening up, including Greece and Iceland, with more expected to follow suit very soon.

Still, there are many unknowns — namely, which countries will open when, and who will be able to enter. As a result, travelers are hesitant to lock in their summer 2021 flights, leaving tons of available inventory — and, at the moment, a glut of premium-cabin saver awards.

For the time being, United Airlines is offering tons of low-level business-class awards, making it possible to fly the carrier's excellent Polaris product at the lowest possible rate. The "usual suspects" — like Newark (EWR) to London (LHR) — have saver awards open for months at a time, but I'm also seeing plenty of availability where it's usually less likely to be found.

As I mentioned, you'll find the greatest number of open seats on United's East Coast-London flights, with at least four Polaris seats available on almost every summer date.

United's other U.S. gateways have great availability to London Heathrow (LHR) as well, including Washington, D.C. (IAD), which is offering Polaris-equipped 777s every day.

Houston (IAH) also has nonstop Polaris availability to London on many summer dates — you'll score a Polaris "pod" on these flights as well.

Nonstop availability is also excellent from Denver (DEN), though some flights might be operated by United's older 2-2-2 biz.

West Coast flyers might need to work in a stop for summer London flights, though there is a fair amount of nonstop Polaris availability for this fall.

Premium Plus is available here and there this summer as well — on some dates, even for less than the cost of an economy award.

London makes for an excellent connection point, too, with easy onward flights to a handful of Star Alliance cities throughout the EU.

It's not just London, of course — you'll also find saver business-class awards on United's other European nonstops, including Denver to Frankfurt (FRA), which also has near-daily availability on Lufthansa's A350 for 17,000 miles more.

From the East Coast, Newark to Dublin (DUB) has decent availability on the Boeing 787-10.

Nonstops to Zurich (ZRH) are open on many days, too, with a slight premium for flights operated by Swiss.

Even Newark-Milan (MXP) has some open saver space, though flights to Rome (FCO) will cost you considerably more.

Unfortunately United's latest additions are not available at the saver level — at least not in business class. For example, Newark to Dubrovnik (DBV) will cost you a whopping 155,000 miles each way.

The same goes for Washington, D.C. to Athens (ATH) — a redeye long enough where it could still make sense to redeem more miles for biz.

Chicago (ORD) is Reykjavik is another route that commands premium awards, though with less than six hours in the air, I'm not sure it's worth the enormous splurge.

Although we don't yet know when you'll be able to visit some of these European destinations, redemptions offer extra flexibility, so it could be worth locking in some saver awards, especially if you already have miles in your United account.

While getting refunds for cash fares can often result in a battle — and, at best, a notable delay — award bookings can offer ultimate flexibility. Cancellations often bump your mileage balance back up instantly, and limited redeposit fees mean the costs of canceling a ticket are minimal (or even non-existent).

That's certainly the case with United MileagePlus — every time I've canceled an award trip, for any reason, my miles instantly reappear in my account. And, if United cancels a flight or makes a significant schedule change, airline agents are typically able to "open up" awards for a different routing or date, making it possible to avoid losing a prized award to a high-demand destination.

Best yet, while some of these saver seats are only available to United elite members and credit cardholders when booking via the MileagePlus program, the majority can actually be booked via partner programs, opening up some exciting deals.

American Express partners with ANA Mileage Club, for example, letting you book a round-trip business-class flight to Europe for 88,000 Membership Rewards points.

For more on using credit card miles to book these flights, see:

• Best ways to redeem Amex points on Star Alliance airlines
• Best ways to redeem Capital One miles on Star Alliance airlines
• The best ways to redeem Chase points on Star Alliance airlines
• Best ways to redeem Citi ThankYou points on Star Alliance airlines

Before you book with a partner (and transfer points), though, there are couple of very important details to keep in mind. If United cancels a flight, and you've booked through MileagePlus, an agent may be able to open up award space to accommodate you at the same rate on a different date.

However, if you've booked that same United award through a partner, you'll only have your pick of current saver availability — or the ability to request a refund to your account. If you've transferred points in to complete the booking, they'll likely be stuck — you won't be able to reverse a transaction from ANA back to American Express months down the line.

In addition, not all transferable point programs process these transactions instantly. As an example, it can take up to 48 hours for Amex points to reach your ANA account. Since the Mileage Club program doesn't allow holds, you'd need to simply hope that the award availability is still there when the miles finally arrive.

Unfortunately this incredible award availability doesn't extend to many domestic and regional flights — United likely expects U.S. travelers to book flights closer to home in an effort to avoid getting stranded halfway across the world or navigate as many restrictions.

As a result, the carrier doesn't have an incentive to open these up for award tickets. In fact, you'll actually redeem more miles for many regional flights — such as United's seasonal nonstop from Newark to Anchorage (ANC) — than you will a long-haul to Europe.

Another downside to limited domestic award space: If you need to connect to reach a long-haul United flight, your U.S. leg will almost certainly be in coach.