May 1st - workers' day - usually marks the first seaside trip of the year for many Romanians. Bucharest will be less crowded with many people going out of town, so if you plan to stay in the capital city you can go out biking. If you don't have your own bike, there are bike renting places across the city: Cicloteque (36-46 Mihail Kogalniceanu St., close to Eroilor metro station; 0755.236.878; paid renting), free bikes in Kiseleff park,  Raitabike (35 Ion Brezoianu St., near Cismigiu park, 0731.006.005).
There won't be as many cars in the city during this week-end to watch out for, but you still need the bike map, you can find it here: Bike Map
Check out the week-end events in Bucharest and on the seaside and take your pick:

In Bucharest

Laser Tag night at Laser Maxx, on Friday, April 30.
Publica concert in Music Club on on Friday, April 30, 22,00 hours
Jet Set Band concert at the Jet Set Events Hall, on Friday, April 30. Playing songs from the 60s to 90s in Romania. Dress code: tie. Free shot for pioneer tie (Romanian communist symbol)
Capitalist May 1st- The I Love Hand Made  products fair at the Bucharest Museum (Universitate square), Saturday and Sunday, May 1st &2nd, free entry
Movie screening, selection by Romanian director Corneliu Porumboiu, at the New Romanian Director Cinema (3 Monetariei St.). Lake Tahoe, Liverpool, Sud Sanaeha, the Belly of the Whale, with English subtitles.
Gallop Show at Arenele Romane on Saturday, May 1st, 20,30 hours
Kumm & Mood concert in Control Club, Saturday, May 1st, 21,00 hours
Directia 5 concert in the Jukebox club, on Saturday, May 1st, 22,30 hours
Vintage hats fair at Serendipity, 12 Dumbrava Rosie St., Sunday, May 2nd, 11,00 – 17,00 hours
George Dalaras concert at Zone Arena, Sunday, May 2nd, 16,30 hours

Seaside May 1st events
Neptun: Friday, 30 April, 19,00 – 22,00 hours – Evergreen Party
Neptun: Friday, 30 April, 20,00 hours – Blockbuster Invasion theater
Neptun: Saturday, May 1st, 21,00 hours – Advertising Night (Noaptea Devoratorilor de Publicitate)
Neptun: Saturday, May 1st, 21,00 hours - concerts Smiley & Band, Fly Project, Puya & Alex.
Constanta&Mamaia: Saturday, May 1st, 15,00 hours Black Sea cruise in the Mircea brig; RON 150/ticket for the 3-hour cruise
Mamaia carnival and flying show on Saturday, May 1st
Vama Veche concerts featuring Urma, E.M.I.L., Viţa-de-vie, Chester, Za duff and Replace, Saturday, May 1st