We are a group of 8 visiting Barcelona at the end of October. We want to find out what is the cheapest/efficient way to transport from BCN airport to Eixample area where our hotel is located?
Most efficient way
The most efficient way is to take a taxi which costs around £25 one way. (Around £6.25 per passenger). The taxi takes 14 minutes.
Alternatively, if you want a cheaper way, you can take the bus A2/46 which takes around 30 minutes and can cost as little as £2.
Alternative routes can be viewed on Rome2rio.
Given the current political situation (as of the 15th of October), I'd watch carefully the news to see how events unfold. Do not assume infrastructure will work according to plan.
There are plenty of political rallies against Catalan separatist leaders' prison terms. Some of these demos turn violent, and they are blocking partially the roads to the airport and trains. Indeed, it's also possible your flight gets cancelled.
It's definitely worth checking out how far your hotel is from the Metro. You pay a bit of an airport premium taking it from BCN. For a lot of people, it's still going to be the sweet spot between cost and convenience, unless you have an excessive amount of baggage.