Yes — Ulcinj genuinely has the most extensive sandy coastline in Montenegro. Velika Plaza stretches roughly 12 to 13 kilometres south of Ulcinj town and is shallow enough for young children to wade safely. It's also a well-known kite-surfing spot because the afternoon wind (known locally as the jugo) is reliable. Facilities are basic compared to Budva, but you get space and sand in abundance.
Mala Plaza is the smaller town beach right below Ulcinj's old town. It's sandy, scenic, and convenient for those staying in the centre — but it fills up quickly in July and August. Ada Bojana, a sandy delta island at the mouth of the Bojana river near the Albanian border, is famous as one of the Balkans' longest-established naturist beaches and has its own restaurants and accommodation.
Ulcinj has a distinctly different atmosphere from the Budva Riviera — more laid-back, with strong Albanian-influenced food and culture. It's generally better value and less crowded, making it a favourite for travellers looking for something beyond the main tourist strip.